K8200 issue with calibrating motors


I’m having a bit of an issue in calibrating my motors, namely the adjusting voltage to 0.425V part. Two of my motors work just fine and can be calibrated to 0.425V but the other two (X-motor and E-motor) seem to skip around that range. They started off in the 0.05V area and turning them to the left (obviously) eventually changes the voltage to 0V but turning the screw to the right makes it skip from 0.05V all the way to the 3-5V range. The 0.1V to 3V range seems to be skipped entirely. What can I do to fix/troubleshoot this? Could it be faulty soldering and if so which pins on the motor connector should I check to ensure they are connected?


Update: I’ve measured the resistances of the motor wires’ A and B poles and found them all to have resistance ~0 just like the motors that work so it doesn’t seem to be a soldering issue. Could this be a faulty board or faulty voltage regulator screw?

I did some more measuring and I’m pretty sure the potentiometers are broken. Resistance between one set of pins is the same as the others but another set of pins shows a huge resistance unlike the ones that work. Could I get a new PCB or alternatively find the potentiometers and replace them myself? If so does anyone know how I can get my hands on a replacement potentiometer?