Cut a slot on the centerline of the stab and elevator where the hinge will be. I start with a razor knife, then open the slot up with a broken off piece of a coping saw blade. Put vaseline on the barrel part of the hinge. Mix epoxy and poke down into the slot to the best of your ability. Smear some more epoxy on the hinge so that it flows through the holes. Put it all together and wipe off the excess epoxy. The hinge pin should be centered on the trailing edge of the stab and the apex of the vee on the elevator.