Vintage Synth Repair

Hi, I'm trying to repair a POLY-61 for a friend. I have very little
0;experience at this.(I replaced the battery in mine so he thinks I'm a
;
genius).
Anyway, I replaced his battery,but some of the ni-cad acid found it's
way across to the voice board. I had to replace a transistor and some
other things. I thought I had it right, but after a few minutes voice
2 and 3 begin to drift up in pitch to no end. I don't know if I used
the wrong parts or if something else is wrong.

Any ideas?