As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
FOLLOW-UP TO #1 IDG FREQUENT SERVICING. FREQUENT SERVICING INCLUDE BEFORE AND AFTER IDG REPLACEMENT. (#PRI2/ETOPS). GROUNDED - YES. FOUND CLEAR EVIDENCE OF A LARGE OIL LEAK FROM THE AIR/OIL COOLER ON #1 ENG. REMOVED AND REPLACED #1 ENG AIR/OIL COOLER REF B737-900 AMM 24-11-21-400-801. LEAKS CHECK GOOD. NO FURTHER DEFECTS OR LEAKS FOUND.