MMU2S PSA: Tighten Selector Screws
Not sure if this is the right place for this topic but I wanted to share. I've had on and off success with my MMU2S, lately more failures than usual. My typical failure these days is the resetting of the MMU right before filament is to be extracted from the hot end. This would invariably result in the filament getting stuck in the hot end and not unloading.
I've been tearing what's left of my hair out trying to figure this out because it just. wasn't. consistent. I was sure the motor drivers were either hitting a thermal cut or there was something related to the friction along the filament path. These are indeed common issues.
Reviewing old threads yesterday led me to check the two screws securing the selector to the selector motor shaft. They were quite lose but not to the point of having backed out completely. I tightened these and voila! Back to running like a champ.
Hope this can help somebody else too.