As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
WITH #1 ENG GENERATOR SELECTED GEN OFF BUS LIGHT ILLUMINATED-AC AMPS AND AC VOLTS INDICATED ZERO. GROUNDED - YES. REMOVED AND REPLACED #1 ENGINE IDG IAW B737-900ER AMM 24-11-11. OPERATIONAL TESTS GOOD. RE-INSTLALED/RE-ACTIVATED GEN DRIVE (AMBER) AND GEN OFF BUS (BLUE) LIGHTS, REF MEL 24-1B.