As I was working to mount the horizontal stab servo tray I was trying to tighten the blind nuts attached to the servo tray mount rails the rear mounting rail popped loose from the former. There was little to no glue holding the rails to the formers. The rails are "keyed" into two formers under the vertical stab to form a mounting platform for the servo tray. It looked as if thin CA or a very thin layer of epoxy was used to glue the rails in place. To correct mine I reglued them and placed triangle stock on the top side (towards the vert stab) to give more gluing area. It would make a bad day if your servo tray came loose too! Glad I found it now.