5i20 7i48

I have no idea where to ask this question, so I thought I'd start here. I'm starting up a Hurco MD3 mill conversion. The mill has Servomate drives and I'm controlling them with Mesa 5i20 and 7i48 cards.

I have a problem with the X axis scale, so I've only been able to move the Y and Z axes. Both of these move smoothly in one direction, but in the opposite direction the whole machine shakes, the ECC (excess continuous current) LED comes on, and Hal Scope goes from a smooth line on axis.n.f-error to a rapidly oscillating line with 20x's the magnitude of the other direction.

If I reverse the armature and tach polarity, the shaking goes to the opposite direction. As usual, I'm clueless and in need of help. Thanks

Thank you Andy. That was the problem.