Ernie:
Yes you should cut a small amount of covering away from the slot & drill a small hole in the middle of the slot, clear wood away from slot after drilling with a hobby knife. trial fit the hinges in the slot, mark the center of the hinge & stick i pin thru the hinge to insure the hinge penatrates both surfaces equally. insert all hinges & install surfaces. make sure the control surface is pushed together all the way. you should have a paper thin gap between the control surface & the stationary component. for example use the wing & aileron, hold the wing @ about a 30 degree angle with the aileron on the high side, bend the aileron down to expose the hinge, drop about 5-6 drops of thin ca right in the middle of the hinge, it will run down both sides of the hinge into the holes you drilled & it will wick into the hinge securing it to the wood. After all hinges are done on this side, flip the wing over & repeat the process on the oposite side of the hinges.
Good luck
Gil