Update on the second Classic... took it apart yesterday after my last post, and glaringly obvious are what look to be the two filter caps busted open, which would have explained at least partly the screen interference years back... so analogue board definitely needs to be coming out for further inspection and some work (probably a full reccap) before it is put back into service. As for the logic board, it appears to have a fair degree of corrosion around and abouts... It appears C8 has leaked goo and pretty badly eaten the legs of a tiny IC next to it. There is also a fair amount of corrosion around the VIA and sound chips which I cannot 100% for certain deduce the origin of... possibly C1 or C2 , but also possibly moisture from an external source? RC2 and UB7 also have surface corrosion on the legs, however the immediate area around C3 and C4 do not show signs of bad localised corrosion as if electrolyte had sat there.

This board may be salvagable if I can find somebody able to solder the IC's assuming they arent rotted out, but it is definitely not going to be functioning in this state. In the meantime I shall check my stash and see if I have any other servicable boards. As I have owned this Mac longer than almost any I still own, and it has come with me to 5 different houses in 15 years, I'd love to get it going again.