I just built a mk3 and I have the latest firmware.
I do initial calibration and everything is fine. I do a test print of a large cube to set the live Z during the first layer. Get it looking nice and then stop/cancel that print so I can try print something I actually want. I cancel the print by pressing the knob and scrolling down to stop print. So far everything works as it should.
Go and start the new print and the nozzle doesnt go to the 'home' position on the X axis. So when it does the 9 point calibration the first point is ok (it is somewhere along the front edge of the print bed but not necessary to the left). When it does the second or third point, the pinder probe over hangs the print bed and when it goes down the nozzle digs into the print bed. Then I get an error about levelling failing and check if nozzle is dirty. Its like it forgets where the home point along the X axis is to start the first of 9 point in the correct position.
Ive tried turning the printer on/off and starting a new print and doesnt work - same issue where the 9 points are right of print bed so when it gets to the second or third point the probe isnt over the print bed and the nozzle sinks into the print bed.. When I go to auto home it is somewhere at front right of the print bed!! When I go to move axis the 0 point is towards the right...
The only way to 'reset' it is to do the self check again. Once that is done I can print and it works fine.
Whats going on? I dont think the belt is jumping a tooth or anything - doesnt sound like it. The grub screw on x axis motor is tight. I loosened the screws at the back of the x axis bearings slightly. Nothing has helped.
I now have a bunch of dents in my print bed now on the front right corner