Yamaha CS80

Has anyone any experience of the CS60?
I have one for restore/repair.
Basically, everthing sounds garbled,
and on depressing just a single key repeatedly gives 
a different sound each time it's pressed.
I have cleaned all key contacts, all front panel
slider control tracks and the preset
pots on the numerous circuit boards.
(Needless to say I have set them back to original
settings!)
Any assistance would be greatly appreciated.
Anyone got any driving instructions,circuit diagrams and/or 
technical info for this beast? 
Willing to pay any costs involved.
Please reply soon.

Duncan