Basically, a defect in the cartridge heater is almost impossible. The extraction becomes relevant when the handlebar must be replaced after a fall. All heating cartridges supplied after March 2017 can be uninstalled as follows:
Remove all parts (grips, levers, fixtures etc.) from the handle bar. Heat the area where the cartridge is glued into to 180°C/350°F using a soft burner flame. Monitor the temperature tightly using an infrared thermometer as temperatures above 180°C/350°F may damage the cartridge. Then pull out the heating cartridge with a pulling hammer or alternatively with a screw and a pair of pliers. Make sure that the connection wires are pushed through the hole in the handlebar tube and that their insulation is not damaged.