Discussion about the Korg PolySix synthesizer

Hi

My P6 has started having a new issue.
The synth sounds really weird. Here are the symptoms:
- When I boot it, it comes up with the arp on, and none of the assigner 
LEDs are lit.
- All settings sound a bit like a unison note gone totally out of tune.
- Freq does not change with different keys, but scaling of the filter 
seems to follow keyboard
- Every 7th and 8th note of the keyboard is silent. The keys in between 
trigger notes (the same one all the time)

I suppose this is an issue with the assigner board(?), but have no idea 
where to start. I recently replaced the optocoupler with a VTL5C1 and 
cured the keyboard scaling issue. I don't think this is related, but 
then you never know, do you?

Any ideas?

/Frank