It wouldn't hurt to rub down the length of the inseert with a rubbing alcohol-soaked towel, either.
I prefer the glass without anything on it at all. Haven't found anything I like as far as a glass treatment. Just keep it clean. I like using 0000 steelwool to clean the windshield while washing the car. Just that, rub the blade down with rubbing alcohol, and renew the blade once to twice a year as needed. Maybe there is a problem with the spring tension on the arm. Does it lift off and snap back to the windshield as it should, or does it stick in place?