And, sometimes, a solid balsa control surface that has a slight bow and is covered with a "monokote" film can be straightened by applying a covering iron to the convex surface to re-shrink the covering. Care needs to be used since the film can still de-gas and bubble (if it does, reduce the heat, ***** the bubble with a pin and work it out with the iron).

At any rate, a control surface that catches or snaps needs to be corrected since that surface will not consistently re-center. As we found on this plane, the hinges are likely mis-aligned and can be easily replaced.