Proper variables to increase dc steppers

Yes I have. Fairly recently in fact. I had an almost identical problem with a DPK7204XDTI box. It turned out to be one of the drive modules in the black box had failed.

I had purchased a replacement drive (a BLD75) but ruined it by trying to use the heatsink from the old bad BLD72 on it. I was not able to fix the BLD75 I didn't have a good one to compare readings with to figure out what I had cooked. I ended up sending it back to Anaheim Automation to be fixed (I think it was a power regulator that was cooked.) I was able to fix the original BLD72 by replaceing two of the output Mosfets and a Darlington transistors and was able to repair the original drive myself,

But first you do need to eliminate your wiring and motor as potential suspects. Wiring can go bad especially in cable chains or other high movement areas. Also check for burned out contacts in the wiring such as where it plugs into the black box. I did replace the motor cable on this before coming to the conclusion that the drive was bad. And the cable may well have been the cause of the drive failing.

You can also try swapping drives (switch the Z with the X or Y) and see if the problem follows the drive.

Here are links to some of the pertinent manuals for the BLD72 (which I think might be the ones in your drive.). If not then you either have something older or the newer BLD75 drive modules.
Look through the troubleshooting sections of these for some hints at finding the source of the problem. Specifically checking the output transistors.
www.anaheimautomation.com/manuals/steppe...%20Users%20Guide.pdf
www.anaheimautomation.com/manuals/steppe...BLD72%20Addendum.pdf

and for the BLD75
www.anaheimautomation.com/manuals/steppe...%20Users%20Guide.pdf

PS the technique for testing the output transistors is different depending on which drive you have.

Interesting.
I just moved the Z to another module on the drive and the problem came with the move,I don't think it's the drive.
I think I'll swap out the motor (I have an extra for my A axis).
I will also dig out some wire and bypass that to eliminate it.
I do have another 3 axis drive I could try just to make sure on that as well,

You have given me plenty to look into.

Thanks