about to fail Inspection for rear wiper

might sound silly but I cant seem to get my rear wiper on my wifes x5 3.0 to make / stay in contact with the rear glass . Therefore its not cleaning the windshield . I thought no big deal until my mechanic fails me for inspection ( in PA you have to get a mechanic to pass you for inspection .) ANyone have any thought here -- I tried adjusting the arm cleaned the spiral shaft and with a small brush but I still cant get it to stay in contact with the windshield .