Discussion about the Korg PolySix synthesizer

I am trying to restore a good old Polysix which suffered from the usual battery leakage and need some help to see on what areas I should focus. It has a KLM-367 board.

The battery was removed and the board cleaned up. The traces appear good, but I should test for continuity for sure. I re-populated the board, and did hear the Arpeggiator work with a nice sound. I could get Cutoff, Resonance and the Envelope to work.

What does not work:

- All Bank LEDs as well as 1, 2, 3, 4 remain ON.
- Found stays ON
- LFO appears to always act upon the pitch
- Voice 5 seems dead. A swap of both SSM chips on that segment did not change a thing
- Sub-osc does not seem to work
- Octave button does not seem to work

Any help on what to look for and procedures would be most welcome.

Yash