As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
MIA - LEFT ENGINE VIBRATION INCREASED TO 4.3 AT 100 PERCENT N1. HIGH FREQUENCY VIBRATION FELT IN ENTIRE COCKPIT WITH LOUD HUMMING NOISE. REMOVED AIRCRAFT FROM SERVICE. ENGINEERING ORDERED FLIGHT DATA RECORDER DOWNLOAD. ACCOMPLISHED LEFT HAND ENGINE FAN BALANCE. REPLACED DIGITAL FLIGHT DATA ACQUISITION UNIT AND INSTALLED SOFTWARE. SYSTEM GROUND CHECKED NORMAL OPERATION.