If you encounter problems with extrusion during either the material loading or printing, the nozzle may require cleaning (see the manual – nozzle cleaning) or even replacement. Also, the nozzle needs replacing if you notice burn marks or material deficiency on the model. Follow these steps in case the cleaning does not help.
Unloading the Material
From the menu choose “Material” and then “Unload the material” option. The extruder should start to heat up automatically. Once the extruder is hot, the motor will start to unload the material.
Unscrew the nozzle counterclockwise (when viewed from below). Use the nozzle key from the Starter Kit box. Removing the nozzle should take place while the extruder is still hot. When the nozzle is loose, take it out using pliers.
Unplugging the Power Cable
Turn off the printer and unplug the power cable. Wait about 15 minutes and let the machine cool down.
Install the new nozzle in the hotend and screw it clockwise using the nozzle key (when viewed from below).