Some door switches ( I'm being non MB specific as I haven't looked at the switch in question ) are adjustable. When new they are at full height and when the door is closed for the first time the stem ratchets down. You might be able to pull the stem out a bit and feel the notches. There is also a chance the notches have worn out allowing the stem to collapse too far. If you pull on the stem and break it, you are doing so at own risk and will need a new switch.