Wendell...this again goes back to that particular kit that you have being a prototype that someone else had, and knew about things like this. After this long it's hard for me to remember everything, but if you're referring to the piece that sits on top of F2....are there lines drawn on the back on the raw wood in sharpie? Those are cut lines. The original piece there was 1/4" too tall. So if you didn't cut it, then you're 1/4" too tall. if it's already glued you need to cut it loose and adjust it or it won't work.

-Mike