K2 plus nozzle scraping, bed mesh constantly going up after calibration - bad unit?

[Mrburns]

Have you checked the two screws on the hot end are tight ?

WARNING - K2 Hot end nozzle assembly can come loose. CM2784

Over the last six weeks (363 hours of printing) I came upon a problem where the filament would not extrude thru the nozzle. The extruder would pulse and then pop up with a CM2784 error. On inspection it would appear that the top of the unicorn nozzle was not receiving enough heat to soften the filament within the nozzle. Therefore the extruder was pushing against a firm and solid filament that would not go anywhere. Further inspection shows that the lower nozzle assembly would flex when chang…