I thought maybe I had the center joiner upside down, but I have the wider side on the top just like the instructions show. The instructions said to have something to keep the proper spacing when you are gluing the joiner into the wing. I put the center piece into the wing and saw that it was the same width as the outside of the plane. When I put the joiner into both wings the center touches the spars on the wing halves, so I thought it would be a good fit. So when I put the wing on for a test fit I was expecting a good fit, well that didn't happen.

I think I will have to pull the covering off the wing and sand it down to get it flat. [:@]