This is to solve a potential problem while feeding to printer's drive gears - while disengaging the Idler, the Pulley was still rotating to avoid grinding the filament (printer is pulling it).
Other filaments could have moved a bit when the Idler's bearings ran over them while the Pulley was still rotating slowly -> the filament could have been moved into the Selector's path causing trouble (especially when not used in the print).
Therefore, the Idler disengages partially now - moves into an intermediate position between the slots.
Then, the Pulley is completely stopped and after that the Idler does a full disengage like before.
DRracer
commented
2 years ago
This is to solve a potential problem while feeding to printer's drive gears - while disengaging the Idler, the Pulley was still rotating to avoid grinding the filament (printer is pulling it).
Other filaments could have moved a bit when the Idler's bearings ran over them while the Pulley was still rotating slowly -> the filament could have been moved into the Selector's path causing trouble (especially when not used in the print).
Therefore, the Idler disengages partially now - moves into an intermediate position between the slots. Then, the Pulley is completely stopped and after that the Idler does a full disengage like before.
MMU-174