Do you know if anything holds the knob in the place on dimmer switch? My 2005 M7 lost the dimmer knob so went to the dealer to pick up the new knob but forgot to ask the mechanic if something holds it in the place and went home to install it however couldnt figure what holds it in place, seems that I might need e clip or something..... looked up the diagram and dont see anything behind the knob.... Anybody out there know the answer???