I've got spare keys for the chroma polaris if anyone is interested.

Also, I recently replaced the now obselete DAC on my polaris with a
handwired socket adapter using an Analog Devices AN7538 DAC. I can
provide the adapter + IC to anyone who needs them or email
instructions.

2 more thoughts (mods that I haven't done yet, but should work-- not
sure when I'll get around to implementing them):
To expand the 8 position resonance control, it should be possible to
install socket adapters to the CEM3372 chips and add a pot to the
resonance input. This would give real analog control of that
function (but it would not be saved w/the patch).

The same sort of minimally invasive mod could be done to provide OSC
level controls and over-ride the muting of OSC2 when Ring is engaged.

I think that the 3 pots could be installed above the pitch and mod
levers.

I hope this saves some instruments. Now that my polaris is
functioning again, I look forward to some playing time.

-Ben