My hotend is lifting in the 2 spots marked on the bed. It starts gradually, but inside those marks, it's .75mm higher than anywhere else. I leveled the machine, then checked the level of the bed, and it's good. I checked the flatness of the bed with a straightedge, and it's good. I re-calibrated the end stops and z height. I did all of these steps with the bed hot and cold, with glass and without. Still got .75 in those spots. I checked the square of the towers against the bed. I have one tower less than the width of the needle on my angle gauge off. I've ran the hotend all over the bed, and it's only in those spots. Any ideas?
EDIT: Following Guanu's sage advice, I was swapping the arms around the towers to see if the low spots shifted, and found a u-joint that had seized up for some reason and was actually turning the axle in the clamp screws. FIXED! I do feel like a dummy for not looking there on my own, though.
