I just got a 3040T and had a similar problem. I had to take the control box apart and chase it through. Turned out the X servo driver was plugged into the A port on the BOB and the A port was connected to different printer port pins than given in any of the 'documentation' that I could find
I also have a problem with my 3040t the X-Axis won't move with Mach3. It just sits there and makes a grinding sound. You can move it with the knob on the Nema Stepper Motor. Could it be the Trapizoidal screw nut? Please help!
Thanks,
Tom Megna