MMU2 spool placement
When the MMU 2.0 unit is changing the filament, it unloads it from the orange/white PTFE tube situated between the extruder and the MMU unit, meaning that roughly 450 mm of filament is retracted. That is why it is recommended to arrange the spool holders at about 400 mm behind the printer.
Incorrectly placed spool holder can cause problems during the unloading or loading phase. For example, if the spool holders are too close to the printer, it may cause problems with tangling and with friction.
The current version of the spool holder is a continuation of the spool holder design used for the first MMU. It has been tested through thousands of hours of printing and was proven functional.
The printed parts attached to the spool holders are designed to create loops of filament instead of letting it fall down from the spool and possibly getting tangled up. It is important to check if the printed arm is firmly attached to the molded tub. Please note there is a groove on one side of the tub - the arm needs to be attached on the same side. Also, as mentioned before, the arm needs to have enough space for its movement.