Y axis freezing during Z Calibration  

Y axis freezing during Z Calibration

Saturday I performed the upgrade of my Original i3 to the MK2. After calibration I had two immediately successful prints using PLA, and an ABS print failure. From what I could tell the temperature balance of the bed and my print room was not correct and the bottom layer relieved itself from the hot plate. This was of no concern to me, it was very late t night so I turned the machine off and waited until the next day to try again. Last night I wiped the hotplate down pre heated and sent the printer to home and performed a Z calibration. As the print head moved to the fourth position (far right center) on the plate the y motor making the movement sounded like it was coming to a grinding halt, and the z axis attempted to lower the head missing the sensor position on the plate by more than half the distance of travel from the third position to the fourth. This crashed the head into the build plate, I stopped it immediately and reset to try again. After another failed attempt I tried the following; manually moving the y axis with the main power disconnected, manually moving the y axis through the LCD/control knob interface, and performing the self test function in the printer menu. The results of each are as follows; Power Off Manual movement- it feels as though it is binding in certain positions, at three points in the travel distance. LCD/Knob interface- Seems to move fine, free range of motion from 0-210. Self Test- as the motor moves to the y-stop it does not stop, it triggers the stop (I hear the clicking of the switch) but continues to push as though it is not triggered, I gave a light tug on the belt and the test stops signalling that the Y axis is"OK". Can someone please give me a procedure to follow to test the motor for a definite go no go on the motor? Or can I simply switch the stop and motor with the ones I have from my i3 setup to test functionality?