As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
KMIA-GUA - FLT 47 - DURING CRUISE, NR 1 ENGINE EXPERIENCED HIGH VIBRATION (2.4) ENG WAS THROTTLED BACK TO IDLE AND A/C PERFORMED AN AIR RETURN INTO KMIA. ON GROUND AT KMIA MAINTENANCE PERFORMED A TRIM BALANCE PER 71-00-00 TEST 7, MAX VIBRATION 0.5. AIRCRAFT RETURNED TO SERVICE. (M)