OK, I see that most of the pics don't show on the threads above, so I rescanned several items. My mirror on the 98C230 is a bit different - it doesn't have the red and green LED assembly on the bottom like your pics. But the following may be helpful.
First are the 2 pics MBenzNL sent me showing the inside of a Euro mirror (which has LED display digits - for temp?):
Next is the inside view of the mirror base showing the horizontal pins and coil spring assembly that holds it to the roof:
Next are pics of the instruction manual that came with my replacement (1998 C230) mirror, telling how to remove the mirror from the car:
Finally is my crude drawing showing the insides, and the 2 spring clips that had weakened and allowed the mirror to flop around. Bending the springs slightly into a sharper 'V' shape fixed the problem for me.
The Euro mirror MBenzNL worked on had a different spring system - a friction collar I believe. But my mirror came apart just as he stated it would (carefully, not breaking any locator plastic tabs, glass surface face down on a cloth covered surface because everything is attached to the glass side of the mirror housing on mine). I don't know what you will find inside your 1994 C220, or if the S class removes/comes apart in the same manner, but the fix was very simple on mine, and if I had known about it before I bought the replacement mirror, I would have saved $300!!!