Yamaha CS80

Hi. 
My name is Tommaso, live in Italy and I had in the last 10 years 
three CS80! 
The second was in perfect condition and 
I sold to a dear friend in Italy. 
The third I found recently, I could not live without a CS!
I started with the restoration.
Now the beast was in perfect condition externally, perfectly tuned 
but with a  little problem on the five Mboard on Channel One.
With the Sine wave only (VCF volume closed)
In addition to sine,I Feel another waveform  similar to sawtooh.
And the waveform (Saw e Square) of the channel one are closed!
I Change all the IGO chips in the Board,but without any positive 
effect.
Then I changed the polarize electrolytic capacitors.

Same problem...

Now,they may be the 1 Uf 50V not polarized capacitors?
Or the other caps?

Sorry but I do not have an oscilloscope.
Some suggestions?