As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
AIRCRAFT WAS GROUNDED: AN EMERGENCY WAS DECLARED AND THE AIRCRAFT RETURNED TO CLT DUE TO AIRFRAME VIBRATION FROM 4R DOOR AND AFT GALLEY FLOOR. VIBRATION WAS MODERATE. 17000 FEET 300 KNOTS AND 250 KNOTS, VIBRATION PERSISTED. THE AIRCRAFT LANDED SAFELY AT CLT WITHOUT FURTHER INCIDENT. MAINTENANCE FOUND THE VACUUM GENERATOR TO BE SOURCE OF THE VIBRATION. REMOVED AND REPLACED VACUUM GENERATOR AND ACCOMPLISHED A SATISFACTORY LEAK / OPERATIONAL CHECK.