My windshield wipers seem to defy my every action. Can you help me?

Here’s the problem: They clear rain & other precipitation for most of their extension, but the last few inches (the area right when they switch from rotating up to rotating down) they don’t clear the area right at the center of the blade. This leaves a messy windshield right where I need to see. Hopefully that is understandable.

I have replaced the blades myself twice, and have even had them replaced by a pro once. With each change of the blades, they still will not work properly. I’m not very mechanically inclined, and I just can’t figure out how to get them to make contact right in that one spot.

It’s been a rather wet winter, and it has made for some tricky driving situations. Any tips on fixing this?