What was found
DURING CRUISE, FL370, THE NR 2 DRIVE LIGHT ILLUMINATED. STARTED APU, CONNECTED TO THE NR 2 GENERATOR IAW QRH. SYSTEMS OPERATED NORMALLY ON APU, NR 1 GENERATOR POWER. ACFT GROUNDED. REMOVED & REPLACED THE NR 2 IDG IAW AMM 24-11-11. COMPLIED WITH THE IDG UNSCHEDULED REMOVAL FOR CAUSE TASK IAW AMM 24-11-11-080-801. FOUND THE FILTER TO BE CONTAMINATED. COMPLIED WITH A FLUSH OF PLUMBING LINES IAW AMM 24-11-41, REMOVED AND REPLACED THE IDG AIR-OIL COOLER IAW AMM 24-11-21, AND REMOVED AND REPLACED IDG OIL COOLER IAW AMM 73-11-06. OPS CHECKED GOOD. LEAK CHECKED GOOD.