Doesn't really require one. If you look at the thermostat, it has two "ears" that lock into the housing. Find a chunk of scrap tubing that fits over the stat down to the metal piece that the ears are part of, and is large enough in diameter that it just clears inside the housing where the ears sit when assembled. Cut of file two short "dog" sections into the tube that will align with the ears on the thermostat, removing the rest of the tube so that the "dogs" stick out of the end of the tube. File off any burrs you created, put the tube over the thermostat in the housing, press down on it and turn it until the "dogs" catch and turn the thermostat, releasing it from the housing.......
