white tube inside (shown below), then screw it to the nozzle module.
8. Insert 1 meter of filament you are using now into nozzle, push it hardly for a while and then pull
it back to get the dirt inside nozzle out. Cut the head of filament and repeat this step again and
again, until the filament flows out smoothly without much resistance.
9. If the above method doesn’t work, you could also use a 0.4mm diameter needle to push through
the nozzle from the outside in. Be careful of the heat when you are doing this. Then continue with
last step.