We just redid a Johnford Super Vertical with Mach 3 and it has been running for about a month with no issues.  This morning we get to the shop and the calibration is off on the Z axis.  We have restarted the computer and even turned the entire machine off to reset anything that might be weird in the settings.  The servo drive has no issues; we reset it to default settings just to be sure.
We can just recalibrate the axis to work but we are afraid that it will do the same thing down the road. 

Any suggestions??

-Chad