Lastly, screw the servos in the proper position on each tray.

I forgot to tell you, the servos are in the trays but loose. When you glue the trays in you have to get the front/rear distance correct to line up with the holes in the hatches. After the trays are in you only have to line them up left/right by sliding the servos to the proper position on the tray and screwing them down.