How to do a basic refurbishment of a rotary dial?

S&H Modell 36
S&H Modell 36

I like working on dials. Many collectors do not, some even hate it and there are those who are afraid of it. So here is an article on doing a basic, simple and safe clean up.

This method applies to most dial designs, as they all have basically the same parts and work in a similar manner. So it does not matter if it is a dial from a ZBSA 24, Western Electric 302 or French U43.

In this case I used a German dial, the so called NrS (Nummernschalter) 36. It is a 1936 design, used for many decades and on many telephones. It first appeared on the Siemens and Halske Modell 36 from 1936, which was the forefather of the famous W48, standard telephone for the Deutsche Post after the war.

This dial was also used on the Heemaf 1955.

First make sure it works!

Heemaf 1955 dial
Heemaf 1955 dial

I cannot stress this enough. There is no point in working on a dial that is broken. I will not magically start functioning properly after a quick clean and polish. You’ll need to do a more in depth restoration or do a proper repair first. If you do not know what you are doing, you may want to take it to someone who does.

Of course you may need to make a small correction or adjustment. For example the finger stop is often bent, inhibiting free movement of the finger wheel.

You may need to oil it first, if it is very dirty and grimy and it does not run smoothly.

So, test it first on an outside line or a small private exchange if you have one. Make sure you test the higher numbers (8, 9, and 0) too.

What are you going to need?

Stuff you need
Stuff you need

Good oil: use good quality oil! Fine machine oil or clock oil. Make sure the oil is silicone free!


Brushes: good hard brushes, do not use wire brushes

Toothpicks: very versatile

Oiler or oilstick (you can use a toothpick if you do not have one of those)


Tissue paper

A rotary dial is a precision instrument

When the finger wheel is released after it is turned clockwise, the dial will return to its starting position giving off a number of pulses. These pulses are generated with a certain frequency, 10 pulses per second.

Typically exchanges will accept frequencies between 9 and 13 pulses per second. If the dial runs too slow or too fast, the exchange will not accept the numbers being dialled.

There is a little more to pulse dialling, like make/break ratio. But this is a basic refurbishment, so we’ll leave it at pulse rate for now.

Basic anatomy


Dial anatomy front
Dial anatomy front

1. Spring housing, in this case it contains a leaf spring

2. Fingerstop

3. Finger wheel





Dial anatomy rear
Dial anatomy rear

1. Shunt contacts

2. Pulse contacts

3. Pulse wheel

4. Governor

5. Wormgear

Disassembly, be careful

This is quite enough!
This is quite enough!

To give a dial a proper clean, you’ll need to partly disassemble it to reach all the nooks and crannies. The mechanical, rear side, usually is accessible, so there will be no need to remove parts there. But the front is a different matter.

Ideally the finger wheel should be removed, but this is not always possible without the spring unwinding.



If you unwind the spring, you will need to recalibrate the dial, after rewinding the spring. That is hard to do without specialist equipment.

Dirt and encrustation
Dirt and encrustation

Older dial designs often do not allow for easy removal of the finger wheel. If that is the case, leave it in place. Otherwise this basic refurb will turn into a total rebuild. So be careful and make sure you can remove the finger wheel without too much trouble. When in doubt, leave it in place and clean it as best as you can.

If you can remove the finger wheel, remove the finger stop too. There is usually a lot of encrustation on the inside of it.


Brush those teeth!
Brush those teeth!

Wash the parts you have removed and polish the parts that go on the face of the dial. Warm water and a little soap work well, leave to soak overnight if needed. The cleaner you get them, the better the dial will look. Polish the parts before putting them back on.

Pick those teeth!
Pick those teeth!

The mechanism and electrical components should not be cleaned with water. We are doing a basic refurbishment, not a full-fledged restoration.

Clean all the gear teeth with a brush, toothpick etc. until they are nice and clean. If the black stuff on the teeth does not come off, put a little drop of oil on it, leave overnight and try again. Do remember to clean of any excess oil afterwards with a q-tip or a piece of tissue paper.

Cleaning contacts

Cleaning contacts
Cleaning contacts

The dial mechanism has a number of contacts that are made or broken as the dial is operated. These contacts are made of leaf springs with a small point, that is coated in a special black substance. This substance ensures conductivity and prevents the contacts from arcing electricity.

Clean the leaf springs by brushing them and do not use a metal brush. And old tooth brush is just the thing for this job.

Do not use a file or sandpaper, or you will damage that special coating. To clean the contacts, I run a piece of coarse paper along them. This is quite enough to clean them. You can imagine that drenching the dial in WD40 or another oil, will not be good for the contacts.

Where to oil and where NOT to oil

Oiling away
Oiling away

Firstly: use good quality fine machine oil. Make sure the oil is silicone free. Low quality oil or the wrong kind of oil will coagulate and turn to a sort of sticky yellow glue. You can probably imagine that this will adversely affect the proper working of the dial.

Secondly, use as little oil as you can. Oil attracts dust and that will clog up the dial. Do not spray it with WD40! (Yes, some people actually do that).

Please mind that this refurbishment has to last for decades and not just a couple of weeks: cheap oil will become sticky after a while and too much oil will attract dust, inhibiting the proper working of the dial.

Put a drop of oil on all the points where parts move: ends of shafts, etc. If there is a leaf spring, it is wise to put a little drop of oil on it, if you can reach it. This will ensure smooth winding and unwinding of the spring.

Please note that there is a very important part that should not be oiled.



The governor is the bit in the next picture on the right. It has weights mounted on a shaft. When the dial is operated, these weights move outward by centrifugal forces thus acting as a friction brake. This part makes the return of the dial smooth and even, thus ensuring a steady and even stream of pulses. Oiling this part really messes up the pulse frequency of your dial. So do not oil this part.

Checking the dial speed, quick and rough

After cleaning, oiling and reassembly the speed of the dial will be altered and the pulse frequency too. You will need to check if the dial runs at approximately 10 pulses per second and that the exchange will accept the number.

This can be done by simply installing the dial in a working phone and test it on an private exchange or telephone line. Please make sure that you also check the high numbers like 0,9 and 8 and not just the low numbers.

3 2 1 let go!
3 2 1 let go!

You can also compare the speed of the dial with another dial (one that works properly of course), by dialing the highest digit (usually zero) on both dials simultaneously and releasing the finger wheels at the exact same time. This gives you an idea if your refurbished dial is running slower or faster that the test dial.

Keep in mind that as the years passed and dirt accumulated in the mechanism the dial the slowed down a bit. Refurbishing will make the dial run closer to its original factory adjustment. It will not suddenly make the dial run too fast (unless you did oil that governor).

My experience is that after a refurbishment as described above a dial will still function properly, but it will run a lot smoother. And of course it is ready for another couple of decades of use.

If you want to read about restoring a entire telephone, you may want to read how I restored an Ericsson type 1951 bakelite telephone.


  1. Hi, I have just purchased a BELL TELEPHONE VINTAGE M.F.G Company, Belgique..From around the 1950s. I’m able to accept incoming calls with it, but I’m having problems dialing out. It works sometimes but not all the time as the dial appears to be sticking/ slow movement. It’s an intermittent problem, it will work when dialing a number then it won’t. I’m in the UK and need some help/ advice…What kind of brand name of oil would you recommend as I have been looking for this ‘silicone free’ kind of oil that you have mentioned but can’t seem to find anything when I ‘google’ it… And how much would it cost to have this restored as I’m in the UK and don’t use euros…Where are you based, or is there anywhere local ie in the UK that you can refer me to…Thanks in advance Barry.

    • Hi Barry, thank you for your comment. BTMC used a number of dial designs and I am not quite sure which one you have there. The erratic behaviour of your dail my very well be caused by dirt or the dial speed is just a little out of spec. In any case, some cleaning will be needed.

      I am not sure which brands are available in the UK but a good quality sewing machine oil will be good for oiling a dial.
      An example of a lubricant with sillicone is waterproof bike chain oil. I do not recommend that for dials.

      I am based in the Netherlands. I can of course refurb your dial, but shipping costs to and fro will set you back at least 30 e.

      I will send you this reply by email too. I suggest you send me a picture of your dial, so I can at least give you some pointers for cleaning it.

      Regards, Arwin

  2. Hello, when you disassemble all that is behind the dial, regarding the spring, it is enough to go slowly by lifting it, to count the number of turn that will do by releasing it. Once cleaned, it’s simple, you count the same number of laps that it did by releasing it and you put everything back in place correctly. This should be enough once everything is cleaned up. I never had a problem with my dial phones .

    • Hi Yuri, thanks for sharing your view on this matter. Please mind that this article is about a basic restoration, so I wanted to keep things simple and for the novice easy to do.
      Besides that, with many dial designs, especially older ones, it is impossible to remove the finger wheel without unwinding the spring.

      In the future I intend to publish more article on this matter, like articles on specific dial designs, how to calibrate a dial without a dial measuring instrument, and how to do full restorations of dials.

      Best regards,


    • Help! I unwound the dial spring without counting the rotations. Is there any hope in recalibrating the dial?

      • Of all the dials , regardless of manufacturer, the main spring has always been pre-set at 1.25 to 1.5 turns.

        Determined that by counting the number of turns the spring had after removing the dial stop (and holding onto the spring when releasing the stop to allow the main spring to release all of its energy, unwind, while counting the turns and partial turns).

        When dialing “0,” that would put about 2 to 2.3 turns into the main spring, plenty of energy to allow the governor to spin fast enough to properly control the dial’s pulsing speed when the finger wheel is released.

        • Hi Craizy, that is not the case for every dial. I have worked on German dials from the 20s with wire springs that require more than 2 turns. I think Ericsson dials from this period too.


    • Hi Yuri .. Old post but in practice, it is completely unnecessary to remove the spring from the dial, a little compressed air is enough unless the spring is broken (it never happens one way or another), or because there is so much dirt (and even then it is rare).

      It happened to me only once that I had to remove the spring (there was a lot of mold and lumps of I don’t know what), I had no choice but to remove it, but in general it’s a full turn and a quarter turn if I remember correctly.

      But be careful because, if you dismantle the entire dial, you risk having to RECALIBRATE everything, that is not really to be desired.

      In reality, it is better to do as Arwin says. bring non-metallic hard brushes, toothpicks, Q-tips etc….

      But i’m sure now you know these things since 2017… 🙂

      • Hi Craizy, as I wrote in an other reply, sometimes it is impossible to remove the finger wheel without unwinding the spring.
        And please mind that some dials have a wire spring that impossible to get at.
        Then there is no other option than to unwind the spring, and counting how many turns when unwinding carefully is a good tip by Yuri. I would not blindly assume that it is 1 1/4 or 1 1/2 turns.

        And broken springs do happen. Especially with leaf springs. Ericsson type 1947 dails are notorious for that. The rust and break.


  3. Hello I am trying to change a telephone dial card in a rotary phone for use in a production of ‘Dial M for Murder’ The phone we have in the props cupboard has a slightly broken plastic cover of the dial card and consequently I can’t see the hole to help remove the face. Do you have any suggestions? I have photos I can send you.
    Any advice, greatly appreciated!

    • Hi Asha, thanks for your message. I also received your email with the pictures. Your telephone is a GPO 700 and does not have the pin hole release, like US telephones.
      Here is a link to a video that shows how to replace your dial label.

      Best regards,


  4. Greetings!
    I have a Bell System/Western Electric C/D 500 12/53 rotary phone that gets dial tone but I cannot dial out. Fixable? Any suggestions?

    • Hi Susan, a 500 C/d should work on a normal telephone line. Perhaps your telephone line does not support Rotary dials and only touch tone? It is a common problem.

      • Arwin, thank you for your response. Other rotary phones on that same line work fine. It’s just this rotary phone that does not work. I can get dial tone with this phone, but the dialing does not work.

        Again, thank you for your response! I await your comment!


        • Hi Susan, either the telephone is wired wrong or the dial does not run at the right speed and needs adjusting.

          The first problem is hard to solve, via this medium. The possibilities are endles.

          The 2nd problem is easy to test. You can help the dial along with your finger, on the return stroke, making it run a little faster. Or you can hold it back a little with your finger on the return stroke, making it run a little slower. If you do this dialing 2 or 3 and it breaks tone, you know it is running too slow or too fast.



  5. Arwin –

    Thank you for your response. The phone jack at the location where I would like the black rotary to be placed is currently a white rotary phone (which works, by the way). I tried the black phone on another rotary-accepted phone jack and I run into the same problem as above. Get dial tone, but cannot dial the phone. To me it seems like something’s askew with the rotary itself. Are there websites (yours perhaps) where I can get instructions on how to look inside the phone and make sure it is working/connected correctly?

    Thanks again!


    P.S. I it normal to have only three of the four colored wires? Red, yellow & green and not black? Could that be the problem?

  6. Many ex-BT engineers are on the Facebook page GPO Telephones and will be willing to offer advice for the phones they used to work on. In the past, we used to change the dial if we thought it would be quicker than trying to work on a dial at the customer’s house or office.

  7. I have a Bakelite 312 but the dial does not fully return to off position. I undone a screw and I think it’s unwinded but not sure any help please

  8. I have an 746 GNA73/1 P>O phone and I was going to put a modern cable on it but Unscrewed the spring loaded screw too much can you tell me how to get it back in to the nut inside the phone

  9. I have a 1910 Rotary dial phone Danish phone I need to know if you have shematics for this type of phone or some idea how to convert from pulse to tone so that I can use it, it is in good working condition, thank you very much

  10. Arwin, I got another fg.tist 282, and it has two issues:

    1) How do I loose the finger wheel to align it with the numbers?
    I have to unscrew that hexagonal central piece? With which tool?

    2) Nobody hear me, and I got a big noise (a crack) on receptor when
    the hook goes up (when I pick up the phone). It seems a power
    overload in some component. Even if I unplug it from the wall, I hear
    that “discharge” (once) if the hook goes up.

    Don’t know If I made it clear, sorry. Any tip please? Thanks in advance!

    • Hi Fabricio, thank you for your message.
      1 Yes, unscrew the hexagonal nut. There may be a little play on the fingerwheel.
      Also, you may want to check if the number ring is positioned correctly. If that does not work, on the back the mechanism is mounted on a metal plate which is fastenend to a plastic disc with 2 bolts. If you undo those you can move the mechanism a little.
      2 is there a diode in the handset? This should prevent loud clicking.
      Regards, Arwin

  11. Hi Arwin,

    I just got a RTT56A, looking like the one one your site ( Most of the time the rotary wheel runs ok but sometimes it returns slow or gets stuck when I pull out my finger. I guess it needs some cleaning so I was wondering if I can remove the finger wheel without worrying about unwinding of that spring you mentioned. Is this also the case for this model? I saw the finger wheel is attached with a single screw but don’t want to unscrew it and find myself in trouble.

    Kind regards,

    • Hi André, I would leave the finger wheel in place, if I were you. Just clean the back of the mechanism, as described above. That should improve the performance of the dial in any case.
      Best regards,

  12. I have an old W49 and have a problem with the dialing. All number dial expect the 3 and the 6. Could you give me an idea as to what I can do.


    • Hi Kevin, this could have a number of causes. First make sure you dial mechanism is clean and oiled, as explained in the article. Have you done that yet?
      The particular dial on the W49 is an NrS38, the same as in the article. Make sure the fingerstop is not bent. Often a bent fingerstop inhibits the proper turning of the finger wheel.
      Turn the dial on it’s side and look through the fingerstop. Give the dial a full turn and check if the fingerwheel does not touch the stop.
      Do the 3 and 6 misdial? Always or just sometimes? How do you know it is the 3 and 6?

  13. Love the site. BTW I’m new at this. Just bought a Western Electric 201 E1 hand set,round base.

  14. No problem dialling out but when this phone is connected and an incoming call comes.,it tingles once and then disconnects the call. I tried another old dial telephone at this point and it works so I know the line is ok. Do you know which component might be faulty?
    Thanks Willie

    • Hi Willie, thanks for your message. I think there is a short circuit in your telephone, especially with regards to the ringer. Probably one of the wires is connect wrong.
      But it is hard to tell which one, as I do not know the make or model.

  15. Help! I unwound the spring on an older style rotary. Is there any way I can attempt to recalibrate it without specialized equipment?

    • Hi Sean, that is unfortunate. If you have a second dial of the same type, you can compare the dial speed.
      The dail, if you dial 0 (for dials with 1 – 0 lay out), it should return to its rest position in about 1.2 sec. You can use a stopwatch, but that is very inaccurate. You can also make a video of it and use it to measure it.
      You can also use software called audacity and hook your dial up to the microphone jack of your computer.
      What kind of dial do you have?

      • Hi Arwin,

        I actually got it back working again! I found that (after being wound around a couple times to roughly the right tension) the dial needed to be at a certain position (judged from looking at the back of the dial) to make the internal connections register as the start position (not a number) – in any other position the phone would not produce a dial tone. However, while adjusting the spooled up dial to the correct place while trying to replace the finger stop, I damaged a small spring that holds a ratchet cog in place. That small spring is about the size of a spring found in a retractable ball-point pen, even a bit smaller. I ended up having to cut most of the spring away and finally got it reattached with maybe a quarter of what was left of the spring. After that I was able (more carefully this time) to get the dial adjusted properly before installing the finger stop to keep it in place, a hard task whole holding the mechanism in place. I did have to readjust it once or twice to dial correctly though, and maybe it is not adjusted to the most ideal spot, but it now dials correctly!
        It would be nice to have something besides my regular phone line to dial into for troubleshooting. This may or may not be a tutorial you wish to do. If you do it, maybe get an already damaged dial to try it on first. I would enjoy seeing a picture or video tutorial on this, as I found absolutely no resources online to help me.
        Having the finger stop also double with that function is a really bad design.
        I found though, after all of this, that the dial now produces an auditable (through the receiver) number of clicks according to the number dialed. I wonder if some wires are touching that shouldn’t be, as my other rotary phones only produce a single click sound for any number dialed.
        The markings on the back of this dial are: Type 24C AT&E Company Liverpool England.
        The phone is quite interesting, as I believe it to be an amalgamation of numerous parts. Sold on eBay from India, it has that old English dial, a cheap modern (probably Chinese) receiver and transmitter, and an ornate brass and wood body (probably from India). I’m guessing the manufacturer (possibly a single person) salvaged some old dials and made some nice devices with them. It arrived a bit out of shape, dial would not return, sidetone was too strong, handset cradle would not move, I fixed the dial & cradle issues and put some cloth in front of the transmitter to reduce the sidetone (which also softened my audio which was good as it made the speakers voice quite tinny). It claims to be a reproduction of an 1885 Siemens Brothers & Co. desk set, but with a dial. If you know more about these phones made in India (there is a number of different models) I’m interested to learn more about them. You can see it & buy it here

        Thank you,


        • Hi Sean, wow. I am impressed. Glad to hear that you got it working again. Sounds like you had a very learning experience.

          For testing purposes I recommend buying a small house exchange for 3 to 8 lines. They are the size of a shoe box and cheap to get. Great for playing around with your telephones and a good start if you are interested in vintage telephony. Make sure it accept pulse dialing (rotary) or if you like both pulse and DTMF.

          In the future I intend to write more about dial calibration and servicing. But articles like that take quite a while to make.
          Thank you for that link. Sorry to say your phone is a novelty phone or fantasy phone. The design is not based on a real old phone. It is a mix up of newly made and vintage parts, like your dial.
          Not sure if that clicking sound is actually a fault. You always hear that faintly and perhaps in this case they did not bother to put in a surpressing diode to make the clicks sound softer.

          • Yeah, I only bought this telephone because I liked the design for my office desk, and it’s something that I feel comfortable messing with. I will be replacing the cords with vintage cloth covered cords soon. Do handsets always use 4 wire cords?
            I do however have a couple of proper antique telephones. The most original is a Stromberg Carlson candlestick with dial and (I believe original) subset box, I’m guessing it’s all from the 1920s. It’s strange though because I have only seen that frame without a dial, and every S.C. I seen with a dial has the dial inset in the base similar to the Western Electric dial candlestick. On mine the dial is fully out of the case, and I suspect it is either a really early one that has been retrofitted with a dial from the factory or telephone company or possibly by the end user later in its life, however the finish on the dial and base match perfectly. It was from a Canadian exchange. It’s nice, however the transmitter makes my voice come through with really poor quality. Will replacing it with another carbon transmitter fix the issue you think?
            I also own a wood Kellogg wall phone from about 1917. It doesn’t have the picture frame routing or cathedral top like the earlier ones, however it does have the long transmitter arm. It has been retrofitted with an older style dial inside so it can make outgoing calls.
            I also got a cheaply made, but ornate, Chinese rotary phone that automatically converts the dial spin into tones, and has # & * on the dial. You may have seen them. My big complaint is the handset frame is made of such cheap plastic it breaks, and you’re left gluing it, as they don’t sell replacements.

  16. Hello,

    I just got an Automatic Electric dial that runs slow, when compared to my working dials it is noticeably slower. When the first number is dialed it goes back to a dial tone, so the full phone number cannot be dialed. How do I speed it up? It’s very clean, looks nearly brand new, so a cleaning won’t help.

    • Hi Sean, you can speed up the dial by tightening the spring or, for finetuning, adjust the governor.
      But your description makes me wonder if your telephone line supports pulse dialling.


  17. Greeting from the UK; thanks for such an informative article.

    Can you recommend any good guides for rewinding and re-calibrating a spring? I have a dial here in pieces and I’m determined to fix it instead of buying a new one!


    • Hi Oliver, thanks for your comment. I do not know of any. The articles I know of are specific for particular dial designs.
      It very much depends on the design of your dial.

      • Hi Arwin, thanks for your reply.

        I’ve bought a vintage tension gauge from E-Bay. From the date and brand, it may well be the exact model used by BT engineers in the 70s and 80s. I suppose I’ll get the spring wound and then aim for ten breaks per second with the gauge.

        Wish me luck. 😉

        P.S. The governor pivot bearing broke, so the tail of the wormgear keeps slipping, causing the dial to stick. I tried super-gluing the plastic back together to no avail. Any suggestions for something which could perform a similar function?

  18. i have a we 1960 500 phone, there is no dial tone when i pick up the reciever, if the goveror needs to be adj does it affect the dial tone? thank you

  19. I have Siemens The tist 277 d, can you tell me the correct wire connecting with current home phone network?

    • Hi, not sire what type that is. I cannot find it on line. Do you have a picture for me?
      Typically for German telephones, if you use an RJ11 cable, red to A, green to B and a wire bridge between EW or W2 to B.

  20. Hello Arwin, I have the same dial on my W48. I would like to replace the dial plate from a donor since the numbers on this W48 are faded away due to excessive dialling — the numbers are getting white, I think the base color of the plate is white)
    How do you remove the number plate [as in This-is-quite-enough picture] ?
    I tried to poke it using a screwdriver from the side, but it was difficult and I am afraid it will damage the side as well. It felt like the plate is glued to it. Are there any holders from the back?
    It happened on both dials i.e. W48 and the donor dial.

    Thank you,

    • Hi Danny, thank you for your comment. That number ring may indeed be glued in place. It may alse be held in place by small tabs on the inner bakelite ring. It depends on the maker and materiels used.

      You have to be very carefull when removing it. You can easily chip the enamel of the number ring.

      I remove them by first removing the finger stop. Under it is a small notch in the finger ring. There I place a small screw driver under the ring and lift it slightly. I lift it just enough to slide some wooden tooth picks in. Then I remove the screwdriver. I use toothpicks or other wooden tools to lift the finger ring off.

      If it is not glued on, you can replace the ring by pressing it back into place.

      Does that help?


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