I just cleaned and recapped the counter board. The underside was filthy, so I thought maybe something got short because of the dirt.
I reinstalled it in the machine (after I finished putting the new caps in), turned it on, and it still remains that only one motor is responsive, but also the problem where spinning the roller causes the supply to stop working is back – but with the take up! So the take up is still responsive 80% of the power ons, but now if I spin the right hand roller by hand, that causes the take up to stop running and the supply to start spinning. When the supply is responsive, spinning the roller doesn’t make it stop. Huh.
Going to replace that chip now.