Bad Driver/Motor combo?

[Hackwood 0]

So, I have a UM2E+ that I'm upgrading to an E3Dv6 hotend. I'ts been sitting, partially disassembled for a few months, and now that I'm finally getting it put back together, I've run into a new problem. The extruder motor behaves erratically, for example during the change filament process, it "retracts" forwards, then advances by retracting. It's also very noisy, and unable to maintain a constant speed. Suspecting the motor, I swapped the E1 and Z plugs on the board (extruder plugged into Z, Z motor into E1) and the change filament command moves the bed as it's supposed to (if it was connected to the extruder), and sending Z commands moves the extruder motor properly (quiet, accurate, and with full torque). So, the board, cable, and motor all seem to be functioning, so what could I be doing wrong?

 

Thanks,

Hunter.