My printer had been working pretty well for a long time. The quality had started to slowly degrade, but I still considered it well within acceptable tolerances. Then, finally, I started experiencing intermittent clogs. I tried cleaning the nozzle as best as I could, soaking in acetone (well, my girlfriend’s nail polish remover), heating the nozzle to 250, changing print settings, etc. Still the problem persisted. As an amateur mechanic, this is when I start replacing parts. A quick Amazon search for bowden parts found the tubing and the clamp thingies on the ends for pretty cheap and another search found the 0.40mm nozzles (something like $5 for 10).
I got the hot end off of the carriage, then heated it to 250 and pushed the latest clog through. I installed the new teflon tube and noted that it’s supposed to push down into the hot end quite a bit. I got the hot end cleared so the tube would sit properly, installed the new nozzle and reassembled the whole thing.
It loaded the filament beautifully and never did the stepper kickback that it had been doing. Now it is printing Benchy perfectly (well perfect enough for me).
Moral of the story is to occasionally just replace that nozzle. They’re cheap, it’s an easy job and it will save your prints.