EZ-Path z axis choppy only when spindle on

[Carmelod]

With our ez path the Z axis works fine while the spindle is not on (not engage)
But once the spindle is engage the z axis movement becomes choppy.
However the x axis has no problem with spindle on or off.

Does any one come across a mproblem like this?

We check the voltages comming into the amplifier board, with spindle OFF
107vdc with spindle ON 105vdc.

Is that enough of a change to cause the problem with the z axis?

Check the low voltages, they are all fine.