Filament stuck in nozzle  

Filament stuck in nozzle

Long story short, I've been having problems with jams ever since I moved from PETG back to Prusa PLA a couple of months ago. I haven't done a huge amount of printing in that time, but usually when I do I've been getting jams.

The last I solved by doing about 10 cold pulls with PLA. That worked for a week, until I tried printing one of the gear bearings from the SD card that comes with the printer. This time, as opposed to previously where the jam would occur about 3/4 of the way through the print, it jammed after printing 2 layers and the filament had cooled in the heat break. Before, the pulley would just eat through the filament.

I needed to disconnect the fan, then heat it to be able to pull the filament out. This happened twice before I did 10 or so cold pulls with the PETG, hoping that would help. It did, and I managed to perfectly print a Marvin, Benchy and Buddy with no issues.

The next time I go to print the gear bearing, it jams in the heat break again, and when I heat it after disconnecting the fan, it's stuck so badly my filament snaps and I'm left without anything to grip onto. I couldn't feed any more filament into it by hand to try and force the blockage through either.

Next, I'm going to dismantle the extruder and nozzle. How can I go about clearing the blockage once I've done that, and stop this from happening again?