Press the lever of the filament cutter backward to cut off the filament.
Lift the front cover of the printing head to remove it. Unplug the port of the ribbon cables of the model cooling fan.
Use a 2.5 mm Allen key to loosen the 2 screws securing the nozzle assembly, then remove the nozzle assembly.
Power on the printer. Holding the nozzle assembly with a pair of pincers, navigate to "Function" on the touchscreen to enter the Prepare interface. Set the temperature of the nozzle to 220 ℃.
Note: The pair of pincers should be clamped at the upper heat sink block position to avoid damaging the heating plate.
Insert the cleaning needle into the nozzle and push the residual filaments out. Remove the residual filaments above the nozzle assembly. Push the needle in and out 3 to 5 times to ensure that the nozzle has been cleaned thoroughly.
Insert a piece of filament into the nozzle assembly. Observe that the nozzle can extrude the filament successfully, then remove the filament.
Set the temperature of the nozzle to 0 ℃. Wait about 5 to 10 minutes for the nozzle to cool down completely.
Put the nozzle assembly in the installation position by aligning it the the screw holes. Use a 2.5 mm Allen wrench to tighten the 2 screws securing the nozzle assembly.
Prepare the front cover of the printing head. Plug in the port of the ribbon cables of the model cooling fan.
Organize the ribbon cables of the model cooling fan. Put the front cover of the printing head in the installation position by aligning it positioning holes.
Set the temperature of the nozzle to 220 ℃. Navigate to "Extruder" and observe the filament being extruded from the nozzle. The printer can work as usual after being re-leveled.