uc100

I have a machine that I built about 4yrs ago. I am running Mach3 with a uc 100 the machine works fine and runs the g code fine.I am using vcarve and the post processor for Mach3
About haft way through cutting it has a problem one of the axes stop working it will be the x/z or one of the y motors will stop working I will need to close the hole machine down and start all over.
Does anyone know what happening or has anyone else had this problem.

If Mach3 appears to be functioning properly, I'd check the stepper drives first.