Faulty Z-Axis motor?
I've just assembled my first Mk3s and it's working great and I'm super happy....but...
When I was assembling it, I noticed that one of the Z axis motors turned freely out of the box while the other didn't. I assumed it was related to the peculiarities of stepper motors and continued the build. When it got to the point where I had to turn the motors manually to raise the extruder, I found I had to initially use a moderate amount of force to make that motor turn, then it freed up like the other.
Once the construction was complete the first print went fine.
However this morning, when I started it up to do another print, the initial leveling failed and I found that the motor had seized again. Again a moderate twist by hand freed it up and it's printing fine now, but something is clearly wrong.