As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
FLT 1584, VERTICAL VIBRATION FOR 20-30S AIRSPEED 321 VIBRATION CAME AND WENT AT CONT SPD SLOWED IAS AND DID NOT RETURN. TROUBLESHOT IAW TSM 05-50-00-810-801A, IDENTIFIED ELEVATOR AT FAULT IAW DECISION TABLE. NO EXCESSIVE PLAY ON SERVOS OR HINGES NOTED; NO ELEVATOR OSCILATION NOTED, ADJUSTMENT OF ELEVATOR WITHIN LIMITS FOUND LT SERVO PITCHING UP WHEN ELAC 1 SELECTED. R & R SERVO SOLENOID OPS NORMAL