A quick tip on clearing / cleaning a .4mm nozzle..... Go to your local music store and ask them to save you a couple of "high-E" strings from a guitar when they replace strings. This guitar string nicely goes thru the nozzle cleaning the sides as it pushes through. If the clog is due to heat creep then use a small allen key (3mm or less), long end heated with a hobby torch to push the hardened plastic back down the heat tube. No more need to take apart the hotend to clean it! Works a charm!