As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
FLT#2466, FLL-BUF. 'DURING LEVEL FLIGHT AT FL350 A/C WOULD SHUTTER MOMENTARILY AND PITCH UP EVERY FEW MINUTES. IT DID IT WITH BOTH AUTOPILOTS 1 AND 2 AND WITH MANUAL FLYING. ALSO WAS NOTED DURING DESCENT THRU FL180; REMOVED AND REPLACED ELEVATOR SERVO CONTROL (34CE3) IAW AMM 27-34-51-400 SEE ITEM 2 (REMOVED AND REPLACED ELEVATOR SERVO CTL SERVOVALVE (34CE1) OPS CHECK GOOD REF AMM 27-34-51) FOR OPS CHECK.'