Milltronics help

I have a Milltronics knee mill that I am trying to troubleshoot and have a few questions.
The computer boots up without any problems. I can program and save files. The screen shows it is a Centurion I ver 2.25. X and Y axis driven by servo motors, Milltronics Model MT30F.
Z axis is manual. Motherboard is a 486. X and Y ARCO boards are Centurion 5

The problem I am having is the X and Y axis are not working correctly. Let me try to explain.

I can home the X and Y, then I can get to the jog page. If I jog X+, the motor turns in a counterclockwise direction. X- rotates clockwise, looking at the motor end. Motor keeps turning if I jog off 0 in either + or - direction, but motor will reverse direction. When I jog to 0, rotation stops. As I jog off 0, each time I press the jog button, the display shows the distance set and the motor increases in speed but just keeps running. Jog distance set at .003 inches.

The Y axis has a different problem. On the Y axis, when I jog Y-, motor makes about 360 degrees in the counterclockwise direction, then stops. When I jog Y+ motor rotates about 30 degrees in the clockwise direction, then stops. Jog distance set at .003 inches.

With the drives off, when I rotate the X motor by hand in either direction, the display does not change. When I rotate the Y motor in the clockwise direction the display will change, but in the counterclockwise direction I need to make about 1 revolution before the display changes.

Things I tried so far.
Switched ARCO boards. Didn't make any difference.
Checked for 5 volts at the encoders. Both had 5 volts.
Checked for open or shorted wires in encoder cables. Both checked fine.
Checked tach voltage. Voltage increases as motor speed increases.

Working on finding a scope to look at the wave forms at the encoders.
Not sure if anyone turned any of the adjustable resisters on the ARCO boards before I received the mill.

One other thing I need to ask about. When I boot up the computer, the low CMOS battery error shows up. I can get the computer to boot up by pressing the F1 button and continuing. Does that need to be addressed before troubleshooting any farther?

Thanks for any comments!