Tom, when did you buy it from me ? I had an issue in the summer with bad brownout programming which causes drives to blow when they get turned off.
What version is the firmware ?
Sometimes a bad motor (with a leaky armature) will tune fine on the bench, but when you mount it back on the machine then it gets grounded and the problem shows up.
Check with an ohm meter to see if there is continuity between the frame and armature