I just recently bought A shark HD pro. it was a demo model on the floor. was trying to use a touch probe it would start the job fine then lose the Z positioning Also heard wired noise during rapid move.
took the z lead screw out and found Bakelite dust from the lead nut had built in the nut and on the lead screw. Cleaned and reassembled Works great now. I will have to do x & y next.
Hope this helps someone.
joewist
Dirty lead screws
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