I noticed my rear window has a slight arc-shaped scratch in the glass where the previous owner must have had too many "dry runs" with the rear wiper. I was going to lift up the rear wiper blade arm to check it's wear. When I lifted it up an inch or so I heard a "snap" like something broke and let it back down. Fortunately nothing cracked or broke. Aren't the rear wiper arms supposed to lift up out of the way like the fronts to change the wiper blades? If so, I'm wondering what the "snap" noise was and if I should carefully try lifting it up again? Also, do they make glass scratch polish for reducing the appearance of the scratches? The tint is on the inside so I should be OK polishing this correct? Thanks.