As stated the x and y are working fine, but the z-axis has strangely started moving with a jerky motion. Even more strange is sometimes is works smoothly and sometimes not. I can kill the power to the boards and sometimes it works fine after applying power and sometimes not. At other times I have to reboot to get it to work smoothly, and again sometimes that doesn't fix it either.

Reinstalled Mach3 to latest lockdown version (Mach3 R3.042.020). Didn't help.

I can hold down the key to move the z-axis and it will take off and run jerky and then take off and run smooth, then back to jerky.

Pulling my hair out.

Wondering if I have a board going bad?

Another piece of the puzzle is when the jerky movement occurs it's only moving exactly half the distance, i.e., tell it to move an inch and it moves half an inch.

I kept my xml file and restored it during the reinstall.

It's intermitent so it can't seem to track it down.

Any help would be apprecitated.

Thanks in advance,
Vogavt

If you have seperate drives for each axis try awapping them around and see if the problem follows, also presume you have checked all wiring is good.
Hood

Will give that a whirl!