As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
DURING CRUISE FLIGHT AT AN ALTITUDE OF FL380 ENROUTE FROM TORONTO-PEARSON INTERNATIONAL AIRPORT (CYYZ) TO MCCARREN INTERNATIONAL AIRPORT (KLAS) THE CREW EXPERIENCED INTERMITTENT FOLLOWED BY CONTINUOUS TO MODERATE VIBRATION ACCOMPANIED BY A LOW FREQUENT "HUMMING" SOUND. HAVING NO ABNORMAL ENGINE INDICATIONS, THE CREW CONCLUDED THAT THE ISSUE WAS BEING CAUSED BY EITHER AN ALTERNATOR OR STARTER/GENERATOR FAILING. THE CREW PROCEEDED TO DIVERT TO DENVER CENTENNIAL AIRPORT (KAPA) WITHOUT INCIDENT.