New weird problem with Z-axis

I've had my stepcraft 840 for about 2 years and use it regularly, but not daily. I have had someone else on it learning and I don't know if they changed a setting I can't find or what the problem is.

I have imported a file from Fusion 360 to cut a piece of aluminum. Everything seems to work fine. I set up my zeros and then run the piece. the first pass works great put when it goes to the to the step down for the second pass, the z-axis zero is 8mm off and instead of doing a 2/10in stepdown its doing a deep plunge and the z-axis zero is not 8mm under the work-surface where I originally set it. I checked the z-axis settings and the steps-per-unit are at 133.3333. All the other settings seem to be correct, as far as I can tell. I can't seem to get this fixed.

Any suggestions??