I have a Chinese CNC machine and for some reason the stepper motor only goes one direction. I push +Z or -Z on the pendant and it will only move one way.

I swapped the Z and X axis at the control board and then the X moves fine (using Z commands) but the Z still only moves one way (using X commands).

I know the stepper is physically capable of moving backwards because I swapped the X and Z cannon plugs where they connect to the motors and the Z would work really jerky and weird (not smooth at all) both directions. It obviously didn't like being hooked up that way but at least it worked.

I swapped the motor direction on the pendant (software) and that didn't fix it either.

Also, twice today I somehow managed to get it to work. Not sure what I did. It was either a connection thing or it was something in the controller software, possibly having to do with the Z axis limits?

Any idea what's wrong or how to troubleshoot further? Do you think it's hardware (like bad connections to the motor, driver, board, etc) or software (like the controller settings).

Thanks so much folks!

[if it helps the Chinese stepper motor is a "FL86STH118A-22" and the controller/board is a "RZNC-05"]