[LeeWay]

I have had odd issues similar to this. I have even sent the drive back for repair and it was said to be okay. They have repaired several drives for me for various reasons. Sometimes it came down to noise apparently. Another time it was the BOB. Two sets of the drive pins on the BOB went bad. It happens. Replaced with identical C10 BOB back then and it went away.

[popenmann]

Another time it was the BOB. Two sets of the drive pins on the BOB went bad. It happens. Replaced with identical C10 BOB back then and it went away.

That's interesting, thanks for the tip. I might try moving the X axis signals to different pins to see if that makes a difference.

BTW I'm using a straight-thru BOB, no isolation or signal conditioning of any kind.