What was found
COMPLAINTS OF STIFF THROTTLE OPERATON LED TO LUBING THROTTLE CABLE, HOWEVER, AFTER SHORT TIME, CABLE BECAME STIFF AGAIN. WHILE REPLACING CABLE, DISCOVERED THE BALL JOINT WHICH CONNECTS THE CABLE TO THROTTLE METERING ARM BENT AND CRACKED APPROXIMATELY TWO-THIRDS THROUGH BALL JOINT. IT IS SUSPECTED THE ROUGH OPERATION PERMITTED EXTRA STRESS ON CONNECTION WITHOUT PILOT'S KNOWLEDGE. SUBMITTER STATES CLOSE INSPECTION OF ALL ENGINE CONTROLS AND OPERATION SHOULD ELIMINATE POSSIBILITY OF FAILURES.