They are mounted with screws which are accessed from the inner door side, behind a triangular plastic cover plate. I doubt yours have simply come loose, they may be disengaged, a feature which keeps them from being broken off upon impact with another stationary object. Try pushing them back into their sockets but if they have been hit hard enough they could have had some of the internal linkages broken wich willl require the entire mirrors to be replaced.

__________________
Chas

Had a 380SL, 450SL, 380SEL, 420SEL, 500SEL

Got a Euro 500SEC right now.