Ok, this might sound stupid, but the last time I had this problem it was on a much older car that had an adjustment screw...
At the end of winter I bought a new set of blades for my '08 GP. I've noticed recently, in the rain, the passenger side works great but not the driver side. It started as just a strip that never completely wiped, now it's the whole length of the blade. The only way I can describe it is that its almost like there's not enough pressure on the windshield from the wiper blade.
Anybody else have this issue? Is it possible maybe I just got a lemon of a blade?
Any suggestions?