Vintage Synth Repair

Got the manual - 

Tossed all tantalyts and tested the cards one by one in a working unit -
 as it is now, I've got all cards running as they should, all pots, 
sliders and switches working, the power supply seems good and the 
wiring does seem to connect as it should - and yet -

not a sound. I'm quite baffled. Any hidden mojo I should know about? 
Some ghost that need secret tuning?


-Mu