You need to check the traces and resolder the chips on UI2 - UI4, UJ2 - UJ6, and UK4.

The chips should still be good themselves, but the corroded solder on them needs to be removed and replace and their traces checked out.

D1 & D2 are diodes though they look like transistors. It is the same ones used in the Mac II series D2 - D6 (see bottom right side of this Mac IIfx schematic):