As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
THE CREW RETURNED THE AIRCRAFT TO LAX FOLLOWING THE NR 1 GENERATOR DROPPING OFFLINE AFTER TAKEOFF. UNABLE TO CONTINUE ETOPS. AFTER LANDING, THE NR 1 GENERATOR DRIVE AND THE UTILITIES BUSS SHED WOULD NOT RESET. CORRECTIVE ACTION: MAINTENANCE PERFORMED A BACK FLUSH ON THE IDG, PER ER/A 585523-14 REV ORIGINAL. ULTIMATELY REPLACED THE IDG, PER B757 AMM 24-11-01. OPERATIONAL CHECK WAS NORMAL. THE AIRCRAFT HAS RETURNED TO SERVICE.