As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
DURING FLIGHT CONTROL TEST, VIBRATION FELT WHEN RELEASING BACK PRESSURE ON CONTROL COLUMN. REMOVED FROM SERVICE. C/W MCN #E270006, ISS #01. CNTRL-COLUMNS MOVE SMOOTHLY WITHOUT BINDING. C/W FCS-RTS TEST REF E175 AMM 27-00-00-070-801-A. NO ABNORMAL NOISE OR VIBRATION NOTED. RETURNED TO SERVICE.