Thanks . It isn't a start up issue (...though it starts on the first note). I was able to see the problem on the oscilloscope (see new photo). There is an arrow pointing to the trouble area. When distortion occurs this voltage still has not changed from the previous note. when the voltage finally moves (usually after a few key hits) the note sounds normal.
It sounds like what you are mentioning Bob. However I get the same results on c39 and ic31 pin3. I have uploaded a painful 2 minutes of audio (folder polysix demo- distorted-korg polysix.mp3). using the arp to trigger notes (you'll get an idea of the problem after about 20secs). I figured it is easier to hear than me try to describe.
I'm happy to replace either or both ic's. Just thought it would be good to see what is happening.
Thanks again