In Out, In Out, shake it all about!!!
It's been a frustrating day for me. I simply cannot get my prusa to load filament from the MMU3. The filament gets fed, enters the extruder then is ejected. Only to repeat this two or three times before finally sitting and beeping.
That gives me an option to read a message about looking at the tip ship and refining the sensor. Or Done. If you choose Done it tries again until the beeps, if you choose the message, then you can read it after which you can only select Done, which fruitlessly continues to try. There is no abandon option to allow you to get to the menu and check the filament sensor etc.
I've checked this sensor so many times, and it is fine. As is the one on the MMU3, and yet still this dance goes on. I remember setting a sensitivity setting on something, but cannot find that now. I think that was to do with the Idler homing though so probably not the problem.
I felt I had two options, 1) come here and ask if anyone knows why this is happening. 2) Go on Bambus site and order an X1 Carbon with AMS which is currently discounted 20%!
RE: In Out, In Out, shake it all about!!!
I had the same issue in, I have to say, seldom cases. At a certain point it was my regular business: MMU3 pushed filament to the extruder, the idler was moving, and then "3d Printer Wars" - return of the filament to MMU3 having an error.
I was checking multiple things: form of the filament tip, temperature, humidity (is the filament really dry?) and all these things have been fine from my perspective. Then I cleaned the MMU3, checked the extruder for any dust inside and recalibrated it. No success.
More or less by accident, I had the feeling that both idler screws had a differing distance to their "exit hole", just feeling that there was a shadow. I put a bit more tension to both screws, putting a allen key behind the screws to see that both idler screws touch it in line with the face of the idlers plastic part. This was my solution and I have not seen issues since checking the idler tension screws. (I hope you understand what I want to say...).
Good luck!