As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
ON CLIMBOUT PASS 250 KTS THE YOKE STARTED TO OSCILLATE IN THE ELEVATOR WITH OR WITHOUT THE AUTOPILOT ON. IT DID SLIGHTLY DAMPER WITH THE LT AUTOPILOT BUT NOT THE CNTR OR RT AUTOPILOT. THOROUGHLY INSPECTED AIRCRAFT, UNABLE TO DUPLICATE.