Z axis problems

[baseball43v3r 0]

Hey all, have a new problem I'm hoping someone can diagnose, out of the blue, my machine wants to print pieces about an inch and a half below where they are supposed to be, and its causing me confusion. the machine will home fine, and the ulticontroller shows a z height of .3mm but it is clearly not at that height, more like 1.5 inches or so. I know my gcode is fine, because it is a part I've printed before with no problems. When I manually try and jog the machine, It can move down fine, but if I try and go back up, it actually just moves back down! I've tried unplugging and replugging, flashing the firmware, rebuilding the part, all with no success. Any suggestions on what to do? I switched the x and z stepper drivers, no difference, and it looks like the z motor is not holding torque, I can pretty much freely spin the z leadscrew. Indicative of a bad motor maybe? I'm not sure what it is yet. I feel like the board may have been corrupted somehow but I've no idea how to troubleshoot this. Any advice is helpful.

 

[phanc60844 0]

I think i read something similar and it was down to a slipping coupling?

Paul