04 car and it just fell off! The black plastic knob is fixed on with a long screw coming up thru the metal stick. The screw had unwound and dropped out. So how the hell do you get to the screw? I didn't fancy a trip to the dealer so I took out the whole control box, dismantled it and screwed it back together. What a stupid design!!!! Anyone ever need to do this let me know.
Steve