Do a search on this site for that issue. It is a common problem with 850's. There are basically two approaches. One is to press down on the arm to "flex" it back into position. The other involves removing some material from the stop, which allows the arm to maintain contact with the windshield. I combined both methods, flexed it first to return to its normal shape and then removed some material from the arm stop. There was a fairly detailed description of how to do that either here or a Bay 13.