How do I rest z axis

[JAZZCNC]

Hi Dean. That is concerning. What must I do to prevent a stalled motor from twisting the gantry? I will do whatever needs doing to avoid that from happening.

It depends if the drives have a fault signal.? If they do then you can use this to control a relay that puts the control box into an E-stop and reset condition then signals to Mach3 there's been an issue so it can stop the G-code. But again your machine is so poorly wired regards Safety that to do this properly will virtually require a rewire of the control box.

If the drives don't have a fault signal then you are a bit stuffed without getting deep into using encoders etc and cross-checking with the other axis.