So what have I tried now:
I tried the reset adjust of the KLM-367 with plugging in a 56K ohm resistor and turning VR1 on KLM-367. It made some constant hissing noise when I turned VR1 counter-clockwise. But otherwise it made no change.
I then replaced IC's: IC30, IC26, IC34 (IC31 was already changed in relation to batteryrepair) and suspicius looking ceramic capacitors (C38, C39, C41). I then plugged the synth back and it is still acting the same way (no sound, most of leds lighting constantly). I then plugged the 56K resistor back in and turned VR1 counter-clockwise. And there is the same constant noise, but also sound generated when I press the keys. Actually I can see that all 6 voices are working as the diodes light up in turn. The synth does not sound right by no means and all the leds are still lightning up.
I wiggled the connections again hoping to find a bad connection - and the connection on KLM-366B coming from KLM-371 actually made crackling noise when wiggled. So I tested the wire and connector and also PCB, but did not find any bad connections. After plugging it back in I could not reproduce the crackling when moving the connector.
So what can I conclude so far?
That the assigner works? That the core of the synth is working as it produces sound?
Input is most welcome!
I guess I will study Vintagekorg.groups some more and maybe replace a few more IC's on KLM-367 as I am getting the hang of it
