Well the "triangle" where the mirror goes comes off without taking the door panel off, atleast in the w123, and i think the w115 is the same. It has a clip at the top that pops out, so just get a screwdriver under that and pry gentle, the top should pop out and the bottom just lifts out. After u take that off there are 3 screws holding the outside "triangle". Take these out and put the mirror in, less than 5 min job
Hope this helps.
1985 190E 2.3-16
1984 280GE Cabrio
1957 220S(running one day, I hope!)
[This message has been edited by AMGmercedes (edited 01-26-2000).]