What was found
LEFT GENERATOR FAILURE OCCURRED AT 37,000 FEET. THE GENERATOR WOULD NOT RESET. DURING DESCENT, A HUM AND VIBRATION OCCURRED FROM LEFT ENGINE. ENGINE WAS IDLED AND LEFT AT IDLE THROUGHOUT DESCENT AND LANDING. UPON INSPECTION, IT APPEARED THE DRIVE END BEARING OF THE START/GENERATOR HAD FAILED TOTALLY DESTROYING THAT END OF THE GENERATOR (UNREPAIRABLE). SUBMITTER RECOMMENDS OPERATORS REPLACE BEARINGS ANYTIME BRUSHES ARE REPLACED, USUALLY AROUND 600-700 HOURS AND NOT WAIT UNTIL 1,000-HOUR OVERHAUL TIME.