Mk4/MMU3 - Randomly ejecting filament & jamming
I built my Mk4 kit about a year and a half ago and it has printed well since that time. I added an MMU3 about 6 months ago and have not had a failure up until now. In the past week, EVERY print suddenly started randomly stopping many times mid-print job with a "filament ejected" error and jams up the MMU. What happens is, it tries to randomly retract the filament, but stops short of retracting it fully into the MMU (it leaves about 2-3" of filament in the bowden tube feeding the hot-end). The MMU then proceeds to try and move to a different position so it can eject enough filament so it can be snipped off. But, since it leaves 2-3" inside the bowden tube, it gets all caught up in the filament selector and jams the entire MMU.
The only thing that I can think of that's changed is Prusaslicer updates and a firmware update for both the printer and the MMU3 to 6.1.3 back in September of this year. FWIW, I've tried slicing models on a different PC (the main PC is a Windows 11 machine, alternate is a Debian Linux laptop) and files sliced in either do the same thing. Conversely, I also have an older Mk3s+ w/ MMU3, as well, (3.14.0 fw & 6.1.3 on MMU3) and that machine has had ZERO issues, remarkably. So, I'm pretty sure its something to do with either the MMU3 or the Mk4 itself.
Any suggestions on where to start looking?
Thanks in advance!