The hotend is an essential part of the heating system, which consists of an aluminum block and a heater and thermocouple. It is responsible for heating and melting the material as well as for ensuring the proper temperature of the material during the whole printing process. Sometimes the hotend can become clogged with material residues and it cannot be mechanically cleaned. A blockage inside the hotend can make it impossible for the extruder motor to load the material and you can hear clicking sounds before and during the printing process. Therefore, when you encounter problems with material extrusion or your prints are incomplete, inspect the hotend and check if it is not clogged. If you cannot clean the hotend or it has become considerably worn (along with the PTFE tube), replace it according to this manual.