As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
RETURNED TO ORD DUE TO A NR 1 ENGINE GENERATOR DRIVE LIGHT. NR 1 CSD FAILED. OIL LOSS EVIDENT ON COWL, CSD EXTREMELY HOT ON ARRIVAL, SUSPECT INTERNAL FAILURE. REPLACED THE NR 1 CSD, EXCESSIVE METAL FOUND ON CHIP DETECTOR. SHOP FOUND EXTENSIVE INTERNAL CSD FAILURE