Hamad bin Turki al Salami wrote in message
...
I deal with a number of vintage devices, refurbishing and reselling
them. One of the annoyances I have is dealing with missing or broken
buttons (and knobs, dials, etc.). As silly as it may seem, something
like a missing button cap, that has no functional effect on the device,
can dramatically lower the value and salability of a device.

Now, if there's an electronic component that's broken, I at least know
how to look for it, by its electrical specs or even its model number.
However, if I need to replace a button, I'm lost. Buttons rarely have
useful identifying markings on them. And there must be thousands of
buttons on the market, with many variations on shape, size, physical
characteristics, ..., from dozens, maybe even hundreds of manufacturers.
At least, so it seems from the searches I've attempted. I've been
unsuccessful at finding replacement buttons and such, except in the
cases where I had the luxury of the specific manufacturer and part
number.

How do you find a replacement button? Are there any tricks to it?
Any hints appreciated.



From tips files on URL below

For making reasonable looking copies of old bakelite or
unconventional equipment knobs.
Requirements:-
Flexible moulding liquid(obtainable from craft shops for casting chess
pieces
etc),polyester resin and hardener,mould release agent if
required,colourant,
broken rare earth magnet,iron filings,modern-day knob smaller
than required knob,engraving tool for vibration.
Procedu-
Clean and polish knob from which a one-part mould can be taken{no severe
undercuts).Fix any old potentiometer to a metal plate locateable to a small
container (for precise alignment of knob),mount with shaft downwards.Remove
grub screw from the origional knob,place a small plug of cable sleeving in
the hole and reinsert the grub screw.Fix this knob to the shaft (fast but
removeable by pulling).Assemble mould jig and pour in moulding
rubber,vibrate
with engraver to rid of air bubbles,allow to cure.
Mix resin and colourant,preferably keep cool to reduce viscosity.
Prepare the modern knob;mark radial position of grub screw on the rear
surface of the knob,repeat grub screw plug as above,fix to pot shaft..Extend
the grub screw hole with a piece of cable sleeving,plugged at outermost end
with glued magnetic material (length just clearing the side of the mould).
Mix hardener with the resin/colourant and pour in mould,vibrate with
engraver as above.
Allow to cure.Demount mould,then with iron filings locate axactly the
extended grub screw hole and drill down to the grub screw,grind rear face of
knob if required,remove plug from centre of knob.
A refinement is to add punched discs,shapes or press-formed domes of brass
shim lightly gummed to the mould base to provide pointers or contrasting
finish.
The colourant can be ground down broken bakelite knobs , if you can be sure
there is no asbestos fibre reinforcement to the knob/s.


--
Diverse Devices, Southampton, England
electronic hints and repair briefs , schematics/manuals list on
http://home.graffiti.net/diverse:graffiti.net/