have a biesse rover 20.have problem with y axes.machine will run for a while then suddenly start making noise in y and then stop sometimes hard.getting codes 66 and 71 i know 71 is overcurrent not sure about 66.have replaced ball screw,thrust bearings,and linear bearings.when the over current happens i can move head so it doesnt seem like the head is binding.any and all help would be appreciated.