Due to space constraints, I had to sell my Polysix. I'm leaving these pages here for reference, but it is unlikely that there will be any updates in this section

---

The key contacts on the Polysix are particularly simple to fix, assuming they're not too badly damaged.  I had about 7 or 8 keys that were totally dead, and 3 or 4 that would sound only if you wiggled the key.  All that was required was a quick cleaning with a pencil eraser.

First you need to open the case.   Flip the keyboard upside down and remove the row of screws at the very rear edge of the bottom panel.  Also, remove the 2 large screws about 20" apart along the centerline of the bottom panel. These hold the rear half of the key assembly to the chassis. 

Carefully flip it back over and remove the 2 larger screws on each end of the faceplate.  The faceplate will now hinge open towards the rear.  Be careful because some of the wiring harnesses are short and you don't want to put pressure on them.  Disconnect them if they will be under strain.   Also disconnect the large connector to the keyboard (it's fairly obvious to spot). 

Next, pull the synth to the edge of the table so the front edge hangs over (thanks to Old Crow for this tip!!).  Look underneath and remove the row of 4 screws under the front edge of the synth. The key assembly can now be removed.  Flip the assembly upside down and remove the screws from the circuit board running along the bottom.  When this is removed you will see the rubber switches that hold the contacts.

Carefully remove the rubber caps (They come off in strips of 6 or 7 caps at a time).  They are held on by little rubber retaining pins; I push the little rubber pins with a pencil to pop them through the circuit board.  Use a new pencil eraser to wipe the tarnish from the circuit board contacts.  Only rub 4 or 5 times so you don't wear out the contacts.  Carefully pinch the buttons and rub your eraser on the black patch on the underside.  Again, only rub a few times to avoid damaging them.

I then like to blow everything off with compressed air (computer duster) to make sure all the dirt and eraser residue is gone. I lightly wipe the circuit board contacts with isopropyl alcohol to remove any sweat or oil from my fingers and allow it to dry.  DO NOT use the alcohol on the rubber contacts - It may damage them.   Reinstall the rubber strips, and reassembe the keyboard.  A note when reassembling: All of these strips of rubber contacts are identical except one of the end units (which has 1 extra button).  When reattaching the circuitboard to the keyboard assembly, make sure all the buttons go through the holes in the keyboard assembly.   If one of the buttons is misaligned it will cause the note to stick on, or not sound at all.