I am sorry for all the people having problems, but my Prusa mjni is finally just workjng and happily printing all the stuff I throw at it. Its been having issues here and there forever. I just figured out that the hotend has not been assembled correctly (heatbreaker to nozzle seal was weak) which became a greater issue when switching to a 0.25mm nozzle. Now after I fixed it, it is just awesome :)
That was part of it for sure, but even on the machines we reserved specifically for experienced users and were personally maintained by myself just had myriad issues. Every first layer had to be watched like a hawk. And they were bedslingers so knocking over prints was a semi common occurence too.