Windshield Wiper Blades KW T-700

I have a 2012 KW T-700 (single, full width windshield) I've tried a few different wiper blades but either want to leave a 4 inch wide "un-wiped" strip across the center of the blade, particularly on the driver side right DIRECTLY in front of the driver's view line of sight. The colder it is the worse the issue will be it seems. I've tried the type that have a single contact point across the center, and I've tried the conventional types that have 8 points of contact spread across the blade and all do the same thing, some sooner/worse then others. I've tried 21 inch blades and 20 inch blades. (one blade mfgr recommends 20 inch which I bought and tried, but our shop uses 21 inch or whatever they use on the freightliners)

Anyone have this same issue with this particular windshield? and If so have you found a blade/size combination that works well (right)?

I'm going to try a "winter blade" if I can find one here in NY pr PA and if that doesn't work I don't know what else to try.

I also know they replaced the windshield some time back. Is it possible to have an out-of-spec windshield with a curvature defect? I'm sire my company would never dream of buying an OEM windshield.

 

And I should also mention that wind speed coming across the windshield seems to be the biggest culprit. While stopped the blade wipes clean and smooth all the way across, both directions. So, maybe the tension (impression) that the arm spring is simply not adequate to keep the blade pressed down to counter the wind trying to "lift" it as it moves across. The passenger side does not encounter that problem but the pivot point is in a completely different location and the wind impact on the blade arm is also different, so who knows.

 

Does a KW dealer only have OEM blades or are they going to try and sell me just another blade and say this is what KW recommends or the same blade the use on the other KW's?

After doing a lot of research, I think "windlift" is the issue I'm dealing with and need a blade that has aerodynamic properties to take the wind and use it to force the blade down into the windshield to counteract the wind trying to lift the blade ... or I could always drive under 45 MPH when it's precipitating.

I ordered a Trico Force "beam" blade from Amazon to be at home when I get there next week but will stop into the next KW dealer next time it's convenient and see what I can come up with.

 

That was my first thought but had hoped a new blade would correct for a weak spring if that was the case and I was going to mention that to the shop foreman when I get back home next week for a few days home time. Something has to be done to correct this very unsafe condition. New arm, new spring, new assembly, new blade, something. If a person makes a regular habit of bending the arm out to wash the window, I could see where the spring may become too relaxed over time to the point it couldn't hold the blade firmly against the glass at speed.