As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
DEBRIEF OF FLIGHT CREW STATES THEY HEARD A LOUD BANG FROM NUMBER 1 ENG WITH AN UNCOMMANDED YAW TO A/C RIGHT AT 38000 FT. ALSO L ENG VIB INDICATION PEAKED AT 3.7. FORCING AN AIR RETURN TO EWR DUE CREW VIB CHECK LIST INSTRUCTION. L ENG BB VIB MSG DISPLAYED ON ECS PAGE. PERFORMED VISUAL INSPECTION OF NUMBER 1 ENG. PHOTOS ATTACHED. REF WORKCARD 19-7200-9-0001 FOR #1 ENGINE REPLACEMENT SCHEDULED PARTS CHANGE