Motor not turning without torque, is it bad?

[Eric Schubert]

I'm reconfiguring one of my focusers with a geared stepper (NEMA11 19:1 gearbox). I've made a couple others with this same motor, and ordered all three at the same time. This one, however, does not turn reliably. Most of the time, it does not turn on its own. If I apply torque to the motor shaft, then it will turn in the opposite direction as the applied torque. Regardless of which direction I tell the motor to move in the MFP2 app, it always turns in the direction opposite the torque I apply by hand. It makes me wonder if the gap or alignment of the coils and shaft is poor, since the shaft turns just fine by hand. I removed the gearbox and had no issues rotating the shaft, no odd resistance or binding.

Is it likely this motor is bad?

[brownrb]

maybe, but I suspect they might have wired the motor incorrectly, a nema11 I have not seen geared before. Stepper online does not have those.

it always turns in the direction opposite the torque I apply by hand
is normally an indication that the stepper wires are wrong.

If you have a multimeter you can measure the coils.
Measure a good one to determine which wires belong together (low resistance between the two wires). Then compare it with the bad one.

It either has the wrong wires or one of the wires might have come off inside the motor

regards
Robert