Any one else have this problem?

I was having problems with wipers, so i went last night and got bosch 20" blades. Noticed when i lowered the arm back to the glass that the base section of the arms seem loose.

The passenger blade leaves a big traingle section untooched. STILL, So i reached out and pushed down slightly on the base of the arm and it wipes good.

Wondering if the arms are worn or what. We were having bad weather last night so i lifted blades off the glass and they are pretty loose and seem like you could pull them of the splines. I can seat them, but as soon as blade hits glass the base section ***** back up gain.

Does this on both arms.