[Phlogiston]

I cleaned mine with a damp rag.

People - I for one - have tried to rebuild the candohm resistors. Opening the outer case is a real problem. The other issue is getting nichrome wire with a high enough resistance for sections with resistance above a couple of hundred ohms. (Nichrome with resistance of an ohm or 2 per foot is available but this would require close to 100 ohms - or more, per foot)

In several radios (2 Zenith Strats) I have used a knife to score the wire, opening all of the windings, so that there is no possibility of an intermittent, and then hid a 20W wirewound under the old candohm for originality/looks. Also got some blowback on ARF from the non-restoration know-it -alls.

The original is insulated with fish-paper (possibly asbestos). If it is not visibly burned or cracked, it should provide adequate insulation for the one-wind on each end of the candohm that is still connected to the circuit.