The under camber 50% score cuts on the FliteTest Old Speedster and the Old Fogey wings need to be opened up a bit before gluing. One way to open the score cut up is to use sandpaper. To get a really even sanding job I use this sanding sled. It is easy to make from scraps. Use pairs of triangles for added strength. The box channels on each side help to prevent warping, especially if you use spray adhesive, like 3M, to adhere the sandpaper to the foam board. It works on both the wing center section and the wingtips. Sand both edges, front and back.