Vintage Synth Repair

When I pull the upper manual's '8 slider to max, the '8 and '16 flutes 
on the lower manual are totally distorted and noisy. I opened the back 
cover to start looking at the problem, and I basically see that there's 
a flat cable going from the drawbar to the main sound board, a 
multiresistor and a diode for every bar, then on the right to it there 
are 6 similar small circuits made of a big electrolytic cap and two 
transistors, marked as #1, #2, #3, #4, #5 and #6. I wonder where should 
I look at...? could it be a bad divider chip ? what circuits should I 
check ? is there a seperate circuit for each bar of the 9 bars ?... or 
an oscillator ?

Thanks for any direction (the 144K is a transistor based "home" organ 
btw...)