Hi all, I have an update and a new question:
I replaced IC33, and the original issue with my 800 being completely unresponsive seems to be fixed! However, new problems have appeared.
It's currently behaving like it needs the factory patches re-written: the patches are playing low clicks and white noise. However, the tape write switch doesn't do anything - flipping it to "enable" doesn't make "TAPE" appear like it should, so it's impossible to put it into tape write mode.
Also, the button "3" seems to be unresponsive, as well as a couple of the keys. No idea if this is related to the other issues or not.
Any ideas on where to go from here? Would IC34 possibly be a culprit or is there something else that may need replacing? I still don't think it's an issue with the switch itself as there's no visible corrosion and I'd never had that issue in the past.
Thanks again, this group is an incredible resource!