I just had to replace the sample/hold caps on my 2nd polaris. If you
are experiencing detuning, inconsistant PWM or poor pitch tracking on
certain voices, you may have capacitors that that failed w/age. It
seems highly suspicious that both of my keyboards went bad and in
both cases it was after a period when the keyboard wasn't used and
the problem was fixed the same way.

They are the .0068F and .033uF caps near the voice chips and they
must be replaced w/polypropropleyne parts. My technician skills are
top-notch and it took me about 90minutes to replace all 24caps. You
will need a solder sucker.

Don't settle for detuned/uneven voices-- change those caps or have
someone do it for you, but be careful not to unplug the battery
backup when you remove the motherboard to desolder the caps.

I'm in Boston if you want me to perform this work for you.

-Ben