Hi!
When looking at your picture I see something that you must fix if you want to keep your plane .
The servos cannot be screwed to balsa longerons!!!!
Instead use 3mm plywood and a router bit in a Dremel to make more sturdy servo trays.These 3mm plywood plates is then glued to triangular balsa stock and then glued to the fuselage sides.
Never ever ever just glue a longeron directly to the fuselage wall. The end grain in the longeron will not provide enough surface area to hold the servos in place when the fuselage sides move under load, and also...balsa is to soft to hold the servo screws in place.

Never ever use metal to metal clevises.

Check your servo potentiometer!