Did a few things (see below the soundcloud link) and here is what it sounds like (it does sound like a Polysix should sound to me judging from Youtube videos but you'll hear me looking to make the Cutoff latch on by varying other pots like Resonance):
Sometimes, from Cutoff Min to Cutoff Max, you also get some Resonance, even though Res is at 0. Also, the Cutoff sweeps up a while, then maxes, then near Cutoff 10, it warbles rapidly. Other pots do seem to be affecting Cutoff sometimes too, like the Effects Intensity pot.
Checked the diodes and resistors around CPU-P1, they look good.
Found that the diode installed for the battery replacement was not connecting well via the via. Reflowed and pushed the diode lead.
Installed new battery holder with leads that I salvaged from my PC motherboard. Goodbye PC. Added new coin battery. Now I can store my Polysix sounds and recall them.
Reflowed all joints on CN10. Now I have a Pulse Train on CN10-5. Momentarily lost Pulse Trains on CN10-6 and CN10-7 but now it seems it's working.
I guess a calibration procedure is in order.
Another thing I'm thinking of is bridging Pins 1 & 2 of the DAC. It looks from the MC1408 that both should be grounded, but.. on my KLM-367, only Pin 2 is, Pin 1 isn't connected to anything...
Yash