OBERHEIM SYNTH

I've been reading a couple of these latest post & I too happen to have 
a question......I'm fortunate enough to own both an OB-8(midi) & an OBX-
a. Neither of the units are "perfect" yet. The "x-a" is missing a voice 
board. Where can I get one of these boards? The "8" has some contact 
issues. When I hold down the lowest "c", there is a 5-6 second gap 
before I hear a sound. Is this strictly a matter of cleaning the 
contacts? A couple of the other keys take a more agressive push to get 
them to sound too. So, does this sound like more of a good cleaning or 
could there be a voice issue going on hear? 
  If more info is needed, someone email me back please and I can 
clarify anything else if that will help. Thanks, Bill.