The switch(s) probably do not need to be replaced! Just cleaned.
Search under my name for the procedure. I have done this several times.
The design of the window switches allows dirt to collect and prevent contact. They are easy to take apart and clean and put back together. Just watch out because they have tiny little ball bearings in them which will easily fall to the floor. I recommend taking the switches apart over an old bath towel. That way they won't roll away.
'03 E320 Wagon-Sold
'95 E320 Wagon-Went to Ex
'93 190E 2.6-Wrecked
'91 300E-Went to Ex
'65 911 Coupe (#302580)