What was found
(CAN) PILOT APPLIED CARB HEAT ON DOWNWIND AND KNOB SHAFT ASSEMBLY CAME OUT IN HER HAND. PUSH / PULL WIRE HAD BROKEN ABOUT 3 INCHES PAST THE END OF THE SHAFT. EXAMINATION OF THE BREAK INDICATED A LONG STANDING CRACK ABOUT 2/3 OF THE WAY THROUGH THE WIRE. THERE ARE NO SHARP BENDS AT THIS POINT, THOUGH THE CABLE IS CURVED SOMEWHAT. NO EVIDENCE OF PREVIOUS TRAUMA TO THE WIRE.THE AIRCRAFT WAS LANDED IN NORMAL FASHION AND SHUT DOWN.