When the skin is cut, pick the foam out of the slots using an X-acto
knife and/or the tip of a needle file.
The vertical wall must be removed completely on the aileron side
and about 1/2 way down on the wing side.
Use a sharpened wire to make a guide hole for the pushrod channel.
The wire ideally must exit near the outer edge of the servo pocket,
close to the bottom skin.