Vintage Synth Repair

My MS-20 is acting up a bit, and I'm wondering if any of you have 
encountered and/or resolved similar problems to these.  The first is 
that if I turn the level control for VCO1 all the way down, and leave 
VCO2 level at maximum volume, I can affect the pitch of VCO2 with the 
scale control of VCO1.  This works the other way as well.  This seems to 
clear up after the synth has been powered on for some time (> 30 
minutes).  The other issue is that even with the cutoff frequency 
modulation level controls set to zero, the MG still has a small effect 
on the low-pass filter.  This symptom also seems to clear up similarly 
to the other problem, but not as consistently.

Hopefully these descriptions make sense.  If anyone has any suggestions 
or possible solutions, I would appreciate hearing them.

Thanks,

George