On Oct 5, 6:40*am, "N_Cook" wrote:
Used by Fender guitar amp company and used eyelets for soldering component
leads into. What was the material made of and how/why does it go bad? I
think of it as whale-hide but its probably something like linoleum ,
compressed linseed etc rather than paper-fibre and lacquer as under x30
veiwing there is no sign of fibrous material

What color is it and how thick is it?

Circuit boards in general "go bad" because they absorb moisture, they
fail mechanically because of stress from soldered parts or the weight
of soldered parts, they become covered with conductive filth, or they
arc-track because of sustained high voltages.