As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
DURING A FLIGHT, THE CREW REPORTED THAT THEY HAD A SMALL VIBRATION IN THE CONTROL COLUMN WHEN THE AUTO PILOT WAS SELECTED "ON". CREW REPORTED THAT WHEN THE ELEV TRIM WAS MOVING THE VIBRATION DISAPPEARED. THE TECH FIRST CHECKED THE TENSION OF THE CABLES AND FOUND TENSIONS WERE OK. THAN THEY FOUND THAT THE ELEVATOR TRIM TAB WAS LOOSE WHEN PHYSICALLY MOVING THE TAB, SO THEY CHECK THAT PORTION OF THE CONTROL AND THEY FOUND THAT THE BEARING WAS CORRODED AND WORN.