I'm having problems with my extruder motor. The filament isn't being feed through properly, it just oscillates up and down, ie the motor moves forward a step then back as step. Problem remains with various Vref (from 0.1 - 0.6 V). When switching the wires for the x- driver, it feeds filament fine. When I switched the actual drivers on the board, nothing changes so it doesn't seem to be the driverby XChris - Prusa i3 and variants