As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
AFTER ENGINE START, SOURCE OFF LIGHT ILLUMINATED ON GENERATOR 1 AND WOULD NOT EXTINGUISH WITH GEN 1 SELECTED ON. ACFT GROUNDED. REMOVED THE NR 1 IDG IAW AMM 24-11-11. DUE TO UNSCHEDULED REMOVAL OF THE NR 1 IDG, BOTH FILTERS REMOVED AND CHECKED FOR CONTAMINATION. NO CONTAMINATION FOUND. NEW NR 1 IDG INSTALLED IAW AMM 24-11-11. OPS CHECKED GOOD.