GECKODRIVE G540 Losing Steps (#1000000)

I know there are million post on "Losing Steps" so sorry for another, but I cant find how to properly trouble shoot my issue. My setup. MACH3 ,4 nema 34 motors, .Z, Y, X_A with A being slaved to the X (specs https://www.avidcnc.com/cdata/cad/sp...spec_sheet.pdf ) a Geckodrive G540 and a 120V power supply that outputs +48v 12.5A. Ok here is the problem, I bought this CNC used and the guy has ran it since 2014 with no known issues, but it has sat idle for about 2 years. When I run it after a long file it loses steps on the X axis motor.( the gantry gets out of square) I noticed it would randomly make a pop noise as when first powering up during the gcode running. Just to test it I switched the X motor cable with the slaved A motor cable at the Geckodriver board ( X cable in A port and A cable in X port, then switched dir in Mach motor setup ) and then the A motor would make a pop noise similar to when it powers up during running the g code. So the problem follows the driver and not the motor if that makes sense and its only on the A drive of the Gecko, all the others seem to be fine. Its like the A output on the gecko is having a small power interruption. The computer is the same one the guy has used since 2014 with no changes, and have I did read on another post that since it seems to be one issue that follows the A output and not other driver outputs, that its not highly likely a PC or Software issue. The guy I bought it from used it a lot and made custom doors for houses. Could this be a GeckoDriver or a power supply problem? How do I trouble shoot either one? Any advice on what to check? Thanks in Advance

Its a very good Question. I'm doing a similar test in a NH 3400. Not sure if the problem will follow the driver or the stepper yet. I'll be looking the answer here.

It sounds like one of the drivers has issues, although it could also be a bad wire, cable, or connection. I believe you can replace the G250 drivers in the G540 without replacing the whole unit; you should contact Geckodrives for advice on how to do that, if they can't get it trouble-shot remotely.