Ender 3 X Axis stops moving mid print at random times, only makes Y movements after

Question

I have an Ender 3 that suddenly starting having an issue. The X-axis belt randomly stops moving when extruding the first layer. It doesn't always stop at the same exact spot, but once it stops, the only movements that are made are back and forth Y-axis movements.

I am able to freely push the carriage back and forth and there does not seem to be any binding. The printer has no issue performing auto home. I've checked all cables multiple times, on the external side and the internal side. The motor does not seem to be very hot if even warm at all. I've even tried swapping SD cards with a known working G-code/printer.

The only thing I haven't tried is swapping out the motor which I can't at the moment all my printers are busy, however, all the threads I've read mention the motor failure is the least likely answer. I'm not sure what would have caused this. All I've recently done is install a new cartridge and thermistor, and everything was working totally fine until I re-leveled my bed a few hours ago, and when I started a new print after leveling this started happening, and was giving me no issues prior. I can't find any similar threads, so I feel pretty hopeless right now.

Answer 1

One thing that would stop the X stepper is if the X-stop limit switch were stuck "on."

The main function of the stop switches on the three axes is to prevent the printer from continuing to attempt to run after reaching "zero" position. If you trip the limit switch, the firmware will decide that you were at the zero for that axis, and offset the rest of the print, but if the switch stays closed, that axis will not move. If I were designing the firmware, I'd probably command a couple steps movement toward positive in the affected axis, check if the switch has opened, and if not stop with an alert -- but especially in older 8-bit board versions of the Ender 3 there was a shortage of space for firmward features (they infamously also lack thermal runaway protection for this exact reason).

Therefore, check if the X limit switch (under the QR code label, just below the X rail) has gotten jammed; if not, unplug its cable and check with a continuity tester or multimeter to be sure it doesn't have an internal problem with the same result.