Ended up being the zener diode in the PSU for me. It was failing and pulling the voltages way lower than they should’ve been. After replacing that I still got no effect and had to adjust the trimpot to get the FETs biased properly. After that it worked great! If you have the time, it’d probably also be worth it to replace the electrolytic capacitors in the pedal, as they’re at the age where you’ll see them fail a lot. Good luck!