When the proper puller is put into the body and adjusted to fit over the mushroomed glow plug, tighten the outer body down unit it tightens against the head of the engine. Using a null inch drive ratchet with the size required extension. Turn the inside of the puller tool counter clockwise while holding the body in place. Turn until damaged glow plug is clear of the engine head. Repeat the method until all mushroomed plugs are out.