[sdiy] Juno-6 repair q's

[RevTor at aol.com]

All,
  A friend of mine has recently acquired a Juno6 thats in need of some help.  Hopefully someone can give a few clues for me.
First of all the key transpose button is stuck on.  The LED is illuminated full time and anything you do is affected by this in the normal key transpose way.  The switch sounds like its working normally but maybe the actual switch is stuck or something?  
and secondly, only every 6 or 7 key presses yields a note.  When I put it in unison test mode then every keypress changes the tone of the output.  So I guess 5 of the voices arent working.  Anything I can do to get further diagnoses info?  Any certain areas/pads to check for voltages or to listen for audio i should know about to help me further diagnose this board?  I have the service docs from the synth.clara(?) site printed out but really these dont help (me) too much.

The boards look clean as a whistle, but the steel case shows some signs of corrosion.  

thanks for any starting points!!!

~Steve M