Jim: You might increase the throws to 1/2" if possible.
:idea: Another thing to try is sealing the control surface gap. This will improve the overall control response and specifically the response at slow speeds.
To accomplish this, use clear tape on the underside of the surface(aileron & elevator). Disconnect the surface from the control rod and deflect it to the top of the wing( or horizontal stabalizer), then seal the gap. Leave a slight amount of slack in the tape. Reconnect and you are ready to go.

Happy landings Tony