I have been using printer hard last year. I noticed some "filament Dust" around the extruder gear that feeds filament. every time I noticed it I was in the middle of a print. Last night I heard a squeaking sound coming from that stepper and I stopped the print. This AM I disassembled the all metal extruder and the motor all clean. I tested it before By plugging in cable and one mounting screw tight for ground. It doesn't feed filament. When I try to spin shaft , it locked, cant move. Shut printer off and I can spin shaft then. Feels and sounds ok, but nothing when plugged in. Think I should just replace stepper? cheap enough I see Thank You, Bruce