Filament is not loading reliably
I cannot get the MMU2S to load filament reliably. Sometimes it works - sometimes not. The problem is that the MMU2S is pushing the filament too far back, so the gears cannot grab it anymore when it is trying to load it again. So far I've tried to adjust the tension of the tension screws, I've recalibrated the F.I.N.D.A, which works just fine now I guess. Also my IR Sensor is working, more or less, reliable. The filament spools are also hanging above the printer as recommended. However, every fifth loading attempt fails on average. Has anyone an idea what else I could do to fix this annoying issue?
“Sometimes it works, sometimes it does not.“ That‘s suspicious. Since FINDA is involved in figuring out how long to pull the filament out, it might be a mechanical issue with the steel ball and/or stringing on the filament tips. One of the frequently suggested LED mods for FINDA makes diagnosis easier.
Also make sure that is is really the MMU pulling the filament too far, not some auto rewinding spoolholder or something similar.
MY guess is that your FINDA sensor is full of stringy filament bits that have accumulated, and now everytime it tries to load it spools back way too much. Try to unscrew your PTFE tube at the MMU and check for debree either visually with a flashlight, or by pushing a piece of filament through.