What was found
#1 GENERATOR CAME OFF LINE DURING DESCENT AND WOULDNT RESET. SOURCE OFF LIGHT GEN OFF. BUS LIGHT. GROUNDED - YES. PERFORMED BITE TEST ON #1 IDG PER FIM 24-21 TASK 801. NO FURTHER FAULTS NOTED. INITIAL EVALUATION REVEALED IDG FAULT LIGHT ON GCU 1. PERFORMED WIRING CHECKS LISTED ON FIM 24-21 TASK 805, NO DISCREPANCIES NOTED. PER FIM 24-21 TASK 805, REPLACED GCU 1 REF AMM 24-21-81/401, OPS CHECK FAILED, SOURCE OFF LIGHT ILLUMINATES FOR #1 GENERATOR. SUSPECT BAD IDG. REMOVED AND REPLACED #1 IDG, REF AMM 24-11-11, LEAK CHECK GOOD, PERFORMED GCU BITE TEST.