As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
FOUND GROOVES WORN INTO SHAFT OF THE 2 SCREWS THAT ENTER INTO THE RUDDER ACTUATOR ASSEMBLY. ACFT IS SET FOR CRUISE CONFIGURATION: DURING FLIGHT, TAIL VIBRATES CAUSING GROOVES TO WEAR INTO SHAFT OF SCREWS AT POINT WHERE SCREWS ENTER INTO ACTUATOR.