There is a screw in the front of the extruder carriage that is loosened to allow the extruder to be removed. I replaced the screw with the screw shown. It sits on the flange that is near where the threads start. The washer had to be cut down in size to clear the plastic sides of the extruder carriage. This allows me to loosen the screw, slide the mounting plate sideways and remove the extruder quickly.