Problems with the abrupt stall were mostly addressed by Harry Riblett, an airfoil designer who documented a procedure to apply a slight reprofile of the wing root airfoil, which softened the stall response of the aircraft without any significant performance degradation. The reprofile presents other unique problems, associated with the way it is applied to the wing upper surface, essentially glueing foam to the aluminum skin and covering with fiberglass. Similarly, the small center-of-gravity range has since been addressed with stretch kits for the fuselage.