Vintage Synth Repair

Hi all, I bought a Paia OZ to fix up and have run across a big 
problem. The low d sharp is giving the same tone as the d key. When I 
bought it the d sharp was only producing static when triggered. I 
traced the problem to a faulty cd 4013 chip and replaced it. Now it 
sounds a clear tone but the note is a d instead of a d sharp. I can't 
figure out where the note value is generated and what I should adjust 
or replace to fix it. I am still a novice to circuit design and could 
really use some help on this one. 

The schematics are here: 

http://paia.com/oz.zip

I asked them first for help but they would not reply.

Thanks to anyone willing to help. I hope I can soon return such a 
favor the the synth community.

Cheers

Jake Fish