My Prusa MK4 started squeaking periodically on fast Y axis moves. Listening carefully I could tell it was from the right side so today I replaced the 3 Y axis bearings as well as the right side smooth rod (even though it looked and felt fine). No more squeak and the calibrations remain spot-on. Seems a bit premature after 46 days printing time but the fix was easy and cheap. Prusa thought based on the sound there was a stuck ball inside the linear bearing.
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