[SiriusHardware]

There are two types of 'repair paint' available and to be honest I would never use the metallic type (originally meant for track repairs) to revive the conductive 'pills' on keyboards. It's too hard, and when repeatedly crushed will just fall apart into metallic powder which will end up all over the place.

There is another type of conductive paint which is black, and dries with a rubbery and flexible finish and is usually marketed as 'remote control repair' solution - it is very similar to the rubber solution used for fixing bicycle inner tubes but obviously has a lot of carbon mixed into it. Because it is flexible, unlike the metal stuff, it is more squash-tolerant.

The rubber bits on the ends of the plungers are probably removable, they look very similar to the key contacts in my Atari ST and I have seen them used in PC keyboards of a certain vintage as well - so it might be possible to harvest a set of good 'dimples' from an old PC PS/2 keyboard of a certain age.