Stepper Troubleshooting.

I have an old VyTek router that I bought used and it has never worked right.
Just looking for troubleshooting ideas here. The problem is this: The CNC
works fine at a moderate feedrate of about 35-40%. Any more than that and
the X axis locks up. Y and Z seem to be fine. I'm not sure how to go about
diagnosing the problem, I think it might be the motor, but at $300 each, I need
to be sure. The motors for both the X and Y axis are Vexta PK2913-02AA
motors. I had some problems with the wiring coming from the controller, but I think
I have that fixed. Any help would be greatly appreciated.

Thanks in advance.
Jeff

P.S.- Anyone know where I can find info on an EMS model PC3-23P7 spindle
(frequency) drive?




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