Vintage Synth Repair

I'm just a hobbyist, but if it were me, I would socket and replace IC10 
and IC11 (both 723's) as well as all electrolytics (C4, C5, C7, etc.), 
diodes and the 2N3055 power transistors in the power supply. They've had 
a hard life. All those parts together will cost less than $20. Then 
before I even thought about hooking up the rebuilt power supply, I would 
look for and replace any shorted components on the system boards. 
There's likely one.

Regards,
Mike