As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
FLIGHT CREW REPORTED AILERON CONTROLS BINDING AND THEN A NOTICEABLE "CLUNK" WHILE TURNING THE AIRPLANE LT OR RT. AFTER THE "CLUNK" THE CONTROLS WOULD BE FREE UNTIL RETURNING THE CONTROL YOKE BACK TO THE NEUTRAL POSITION. AUTO PILOT SYS WAS NOT ENGAGED WHILE THIS WAS HAPPENING. CHANGING THE AILERON AUTO PILOT SERVO FIXED THE PROBLEM.