Sorry about the delay,
No I have the later model the KG-3925 CNC Router Frame 39x25x5 '05 model with a physical precision metric ball screw, the step per are set to 10,160.
My motor are the DMG DAE HWA DC motor's with US Electronics encoders.
I'd first check in the "port & pins" to make sure your X Y Z signal's are enabled and are set correctly for Dir and setp (I've made this mistake before) and check your "motor tuning", because I have metric my steps are setup for 10,160.
I've gotten humming from having my Kernel speed set to 4500 and not having my motors tuned correctly.
Mach will leave all of your files untouched (besides the default Mach files like Mach3Mill.xml), you could try a number of diffrent setup files just give them diffrent names.
Which ver of Mach 3 are you using?
I'll try to think of other possabilities