On Tue, 1 Sep 2020, Liam Proven via cctalk wrote:
This and the rest of what you describe sounds quite
like the damaged
caused by electrolyte leaking from failed capacitors. This is probably
the most common cause of failure in electronics after they get to 2-3
decades old.
There was one particular time when this happened prematurely:
https://en.wikipedia.org/wiki/Capacitor_plague
There was the issue with the quaternary ammonium salt system earlier on
too, e.g. with Chemi-Con SXF parts and several other ones from various
reputable manufacturers in early 1990s.
Maciej