Rear Wiper Issue

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I have an '04 3.0, and just recently my rear wiper is missing alot of the rear window when wiping. If I'm looking at the rear window/wiper from the side of the car, it probably only wipes the bottom quarter of the window (where the angle of the window is at its steepest). It doesn't even make contact with the upper half of the window where the angle of the window changes and isn't as steep. The wiper is probably like a 1/2 inch off the window when it wipes over that part. I've replaced the wiper blade and made sure the wiper blade/arm is pushed all the way against the window but the issue still happens. Anyone ever have this issue? Do I need to have the wiper arm replaced or something?