Thanks Tom, for your help. The spikes that I was referring to are the output section of the plot. They are also mirrored on the error plot as position error. As I increase the P gain, the frequency of the spikes increases, to the point that the axis motion is smoother and quieter (with the same move distance). With very low P gain (1.0 or less), the axis motion is noticeably jerky and noisy.

I will try the filter.

On the original machine drive to motor connection, there were rather large transformer looking devices labeled as inductors in line between drives and motors. Can you tell me what they are for? Are they or some form of them needed with the AMC drives? Could that have anything to do with the spikes I'm seeing in the output plot?