My Mini won't calibrate

I switched out the nozzle for a .4mm and put everything back. Now it won;t autocal. It sometimes reads the first sensor, sometimes the second. Most of the time it goes too far, cleans the head, tries again then nothing. There is no goo on the head. Can anyone help?

Did you use locate to secure it? It may not have conductivity. You can test for that with a multimeter. With the machine off and the hot end disconnected (unplugged) measure conductivity from the nozzle tip to the hot end ground wire attachment screw on the heater block. If you aren’t getting any conductivity, pull the nozzle and clean the threads and the nozzle seat on the heat block. If you print abs, disassem Ling the heater block and removing the heater core and thermistor and then submerging just the threaded nozzle mount hole in acetone for a while can be effective.

Other possibility is that the new nozzle is somehow short enough that the nozzle can’t go low enough to contact the washers, but I don’t think that’s likely. A third issue would be loose wiring on the bed side or at the hot end connector. Use the ohai kit documentation and trace the wiring harness back to where you lose conductivity.

If it is pushing the bed down you have connectivity issues. Be it wiring or some kind of coating on the new nozzle.