Mk3 Crash
I have a MK3 and im printing lithopanes with it that are almost max height (206 mm z) and twice once ive gotten near the top (maybe 80%?) the x axis starts grinding against the right side and it crashes. If i have it restart it auto homes, but it thinks its about 140 mm further to the left than it is (auto home usually places the head in the front left, this was "homing" almost all the way to the right). Then it would try to move right only to immediately hit the edge, grind and crash again. Both times going into calibration and re-calibrating would fix this.
Re: Mk3 Crash
A photo of the problem will help.
Guessing though --- I'd suggest the part is lifting off the bed in the corners. This warp causes the nozzle to wear into the part and eventually plugs the nozzle, the part breaks loose, or even stalls the motors (leading to wrong coordinates).