Discussion about the Korg PolySix synthesizer

Hello,

This is my first posting - I've recently become the owner of a 
slightly battered Korg Polysix. Everything seems to be working ok 
memories, controls etc (although the battery mod will need carrying 
out), the problem is the way it sounds. 
Although the machine basically seems to be in tune, it seems that 
some sort of high frequency modulation has been superimposed on all 
the oscillators – viewing the output on an oscilloscope shows
this to be the case, all six voices behave the same, so I think that 
the fault lies on the pitch CV generation. This modulation is not 
related to the MG.
Looking at R152 on each voice block with the `scope shows a
sawtooth wave, should this be a level DC value? Also the waveform at 
the V/Oct test point has a large step in it even with all six voices 
at the same pitch.
Has anybody got any suggestions of what may be causing this, and 
where to start checking.

Regards

Adam