I have a problem. I printed earlier with the 0.2 mm nozzle but none of the prints really went well. So I wanted to switch back to the 0.4 mm nozzle. It seems the nozzle is pretty much stuck. I can't unscrew it. (I don't want to use too much force and maybe damage the extruder.)
I've had that exact problem, I guess your nozzle, like me, leaked some plastic, you will have to put more energy (I had to force a lot to remove my 0.2 nozzle).
Heat the nozzle with preheat, extrude or withdraw. Give it another go, use welding gloves
You can break the nozzle if you use to much force leaving some brass in the heating block
Okay guys, I managed to remove the nozzle by heating the extruder while unscrewing it.
However the plastic part at the top got unscrewed as well and was left in the extruder. I had to unscrew some parts from the extruder to take it out of the top.
(some of the "wool"(?) near the heating element came out as well. I pushed it back though)
It seems the PTFE tube melted/clogged and it got stuck. (also notice the dark color of the screw)
I assume it's broken now? Or can I reuse it in the future?
The thread looks okay, you can use it as backup when your real backup nozzles are used.
I used to soak nozzles in acetone when they got stuck with ABS. I don't know what to soak in with PLA. Remove PEK, soak, clean bore and clean thread so you can reuse the nozzle.