0.4 nozzle don't print right

about a month ago, I had a piece of filament stuck in the extruder. After a lot of work I realized I could not get it out so put in a new extruder assembly. The printer worked fine for a couple of weeks then all of a sudden nothing would extrude. After putting on a 0.6 nozzle, everything worked. So I replaced the 0.4 nozzle. But now things get weird.

With a brand new 0.4 nozzle, I would sometimes get a first layer that looked good sometimes not, but after 3-4 layers the print fell apart. and then nothing extruded.

I tried everything, and then I thought let’s try the 0.6, and it worked. perfect print, the 0.2 same, but when I put on a 0.4 (tried the original and the new one, same thing happened.

Does anyone have any idea what is going on?

Thanks

John

Check to make sure your heatbrake fan is plugged in and spinning

If many nozzles are all failing quickly into a print, no cooling could be contributing to that.