St3 Probe Head problems

[[Ke...]]

I have an ST3 probe head on my Zeiss Eclipse and sometimes when the probe head is moving It will move in a jerking motion and make a clicking noise. The light on the probe head will flash between red and green as it is moving in a jerking motion. I have cleaned every thing thinking it could be a bad connection. I am wondering if the probe head is starting to go bad. Have any of you CMM guys experienced this? What are your thoughts?

Thanks
Kevin