I thought i would post my results in the off chance it may help another new person if they have a similar issue as me with the high-z s model.
It turns out it was me, i was driving it too hard at 45mm/sec and as Jazzcnc thought the bushes were getting too hot and were binding, i have now run at both 20 and 30mm with total success, just it ran longer obviously, the model above mine the t series does not have the same bushes so i imagine the problem may not occur so easily.
Thanks to Jazzcnc and Philip at Protools who walked me through the reasoning.
One happy camper again