Hm, a chipram mod that was removed might explain it, though I have no idea what this actually does. I checked the motherboard once again, and found a jumper that seems to have been tampered with.
Somebody definitively has been working in here, the machine seem to have been built in 1990. The Fat Angus seems to be from '93, and is probably added later. Are there any compatibility issues with that?
Yep, I'll try the isopropanol and silicone grease routine on the floppy drive later, maybe that'll do the trick
Without the 512 k expansion in the usual slot, it reports 362736 free memory in Workbench, so there's no extra chipram there now. This is the whole thing:
Yes, I guess I'll change out the Gary and see what happens then. I haven't got a spare, but I found a german gentleman on Ebay that had a Gary with a production date that's just a few weeks off the rest of the chipset.