I like to share this solution because this problem can
lead to confusion and is simpler to what in principle can seem.
When I buyed my Polaris II, I' m very surprised about his state....absolutly perfect....unused, like new, incredible!
I usted one month, and one day when power up, two OF six voices are out of tune. I stayed many hours with my technician, and finally we found the problem ( not easy ).
We replaced green capacitors arround of cem 3374 (333 & 682), works better, but not perfectly....we replaced the same capacitors but Orange and biggest (two of 682 on right part and two of 333 on left part ) and eureka....goes perfectly and better!!!
Logical, since capacitors lose properties with over the years. Now turn the of all voices, and those who are next to the cem3372... sounds richer, with more harmonics.... highly recommended. I've put them in 10%, but if 5% better.
I hope can help with it ;-)
Best,
Jordi