Sure. I could do 0700h AEST on Saturday here. Which would make it something like 1600h Friday in Maine?

Okay I told him about it and he is ready for you ... He thinks he knows what to do so we have hope

I hope you guys will post the results here for everyone else to see. I’m not having this problem, but it’s kinda like listening in on a party line and I’m courteous how it all works out.
Thanks
Art

We sure will I want to know myself what's up!

Any progress on identifying this fault Brian?

Mach 4 gave me a good one today.... Thankfully I was checking the toolpath screen carefully. In the first attachment you can see that the tool path has nearly duplicated itself but approx -50mm in z  Which would have driven the endmill into the bed. After a regen of the toolpath all is well again. (See attachment 2)

The GCode is attached at 3.

It looks like you have something shifting your set point. Like re zeroing your axis would do.