one thing to check also on cs-80 ! if you slide the modules chassis up and down a lot ,,, check at the black wires junction that there is no broken or corroded wires or on the verge of breaking . On mine moving up and down the rack a lot , the main GND 2 black got broken ( +8.5V/-6.5V ) .. so the supply lost ground reference ,, the synth was working but the positive and negative rails were moving ( floating ) in parallel up and down moving the keyboard controls levers . That was a bitch to debug ,, it is not evident to see a broken wire at that location ,, there are so many grouped there .
for your problem : you have output on pin 8 of IC5/CP5 , but cannot control VCA/IC6 when triggered . Have you checked if you receive the trigger signal at TR(63) ( broken/corroded/cold solder ) . if yes check your EG signal scope/meter TP2 if yes them funky final vca IC6
You seem to be in control of that bug , you are not far from a solution , nice work DUDE ! check for cold solder joint with freeze mist (were talking about heat related bug )
remember that the trigger is for both voices so if the other voice is working it is not the trigger circuit . check for trigger signal first , could be a corroded or broken wire ( white as i remember ????) so many colors .
hoping IG00159 is good ,, there is plenty of VCA out there but way less IG159
