I just posted this in another thread, so I'll cut and paste it here as well.

This is why you DON'T want to put CA hinges where the old ones were:

CA hinges MUST be attached with THIN CA.

Thin CA works on a capillary principle, That is, it need the pores in the wood to seep into (one reason it likes your skin so much). But once a hinge has been applied and removed, the pores are already sealed by the old CA, so you either need fresh wood, or (if that would place a hinge too close or too far from the end of a control surface) drill a hole where the old hinge is, and epoxy in a hinge point.