I am going to see if I can remove it. I feel because of this piece I am getting water in that corner. Looking at the pic you can see black mark which I think is from the rubber seal when opening and closing the slide and when the slide is open is not making a good tight seal. What you think Frankie?

I agree. Try some fiberglass tape.Paint it white.

I removed the piece from the corner and saw no reason for it. I did notice when the slide open the rubber seal at the bottom corner does position itself like the right corner. What I am going to do it position it by hand for the next rain. This piece that I remove has nothing to do with the position of the rubber seal because I have checked with it and without it.