Vintage Synth Repair

I have more information on my DS-1. Basically (if I remember 
correctly) it is the middle D note. It plays something between a 
(lower) A to A#. It is only slightly lower than what it should be. 
All the other notes around this key play correctly. Also if I change 
the pitch of either oscillator this one note does change in 
accordance. Does anyone have any idea where I can find schematics to 
either a DS-1 or a DS-2 or any ideas what the problem might be. I 
have heard a few suggestions, but I'm taking all help and ideas I can 
find.

--- In vintagesynthrepair@yahoogroups.com, "ahfinnie11" 
<heathfinnie@y...> wrote:
> I'm thinking of buying one and was wondering if anyone has any 
ideas 
> why only one key would sound a different pitch than it is supposed 
> to. It is also believed to be not a contact problem.
> 
> Thanks