Ditto on drilling a hole in the middle of the slot so the CA can get al the way to the end of the hinge.
Push a straight pin through the middle of the hinge so when you place the control surface, the hinge will not be pushed too far into the slot.
Bend the control surface down as far as it will go while keeping it butted against the pin and add the CA, turn the stab or wing over , bend the surface in the other direction and add more CA (2 to 3 drops per side). Remove the pins and your done.