Maybe I'm not duplicating your question or the problem. Look at the attached image. The sleeve (or barrel) is snug, but slides axially through the hex nut. When the door initially closes on a new switch, the door presses against the plunger, the mushroom head of the plunger presses against the end of the sleeve, pushing the sleeve through the nut into a new position that sets the plunger height, allowing the plunger to slide in and out according to whether the door is closed or open.