I have used one like this before. There are others out there as well but the concept should be the same. It would help ensure you are level across both of your lead screws.
https://www.printables.com/model/7467-tool-to-level-x-axis-of-prusa-i3-8mm-rods
Have you put the printer through the xyz axis calibration as part of your troubleshooting?
https://help.prusa3d.com/article/xyz-calibration-mk3-mk3s-mk3s_112351
https://help.prusa3d.com/article/ambient-temperature-check-mk3-mk3s_161230 if that triggered something sounds quite wrong. Might be worth going back through support again