MMU2S no longer loads to nozzle
I've owned the MMU2 since it was released, and it has largely been trouble free. Suddenly (on filament change 17 of a print) it is no longer able to load filament to the nozzle. I can load filament in all of the 5 slots, and the load goes as normal. When I either try to print, or use the Load to Nozzle feature, it chooses the correct filament, rotates the idler bearing to the correct place, and begins to advance the filament. It advances approx 30mm and the FINDA sensor acknowledges the filament is present, then it reverses and backs the filament out. This repeats 3 or 4 times before it gives up.
Things I have checked already:
The filament path is clear and frictionless all the way through the mechanism
The selector is aligned properly
The correct idler bearing as selected and proving proper pressure against the toothed pulley gear
The toothed pulleys are aligned properly
The FINDA is reading 1 when the filament is present and 0 when it isn't
I've restarted several times, but none of the slots will load to the nozzle. I'm goin to try reinstalling the firmware. Does anyone have any ideas if that doesn't work?
Update: I reinstalled the 1.0.6 firmware and even performed a factory EPROM reset, but it's still behaving the same way.
Could be a long shot but how tight is your PTFE tube and what does the filament tip look like? I had a similar issue and it turned out the MMU2 wasn't able to push the filament through because the tip was too thick so it got stuck. And since the filament wasn't reaching the sensor on the extruder body, it gave up.