I checked the I/O board, and the capacitors (3 of the can-type ones) are leaking. There are 2 large capacitors, but I haven't checked. The engine of my LaserWriter is dated January 1989, so it doesn't surprise me. I don't think the IIg board came very far after. Luckily my dad is interested in replacing them (he has soldering skills, I don't).

So LaserWriter owners - check your boards...problems may be related to leaking caps.