After replacing a stepper motor supplied by support, & having the same malfunction with it about a week later I figured it had to be something inside the motor itself. The motor rod was able to be spun by hand but would not move up or down,only able to twist.
A print had failed when the motor rod went down and not able to rotate back up. I even soaked it overight in ISP thinking resin was the jam $ No change
I pryed open the base of the stepper motor by pulling it up and off the metal housing. What was underneath was a ball bearing that was way out place. I put the ball bearing back screwed it back together (which wasn’t as easy as taking it off. I was able to super glue the plastic base back to the metal housing. reinstalled and ran a few empty prints to see if there was a change. And yes. The stepper motor has been repaired… At least to a functional state. Seems like there was a lot of stepper motor problems for this older form 1+ models & for me the case was the ball bearings were loose causing the rod to spin but removing the needed pressure for it to move up/down like it should…
I got the machine on ebay, so it wasn’t in great condition… More of a test machine before buying a brand new model…