What was found
LAX FLIGHT NR2389: NR 2 DC GEN CAUTION LIGHT ILLUMINATED. WENT THROUGH CHECKLIST AND NR 2 DC GEN DID NOT RESET. SHORTLY AFTER NR 2 DC GEN HOT CAUTION LIGHT ILLUMINATED AND PER CHECKLIST, LEFT NR 2 DC GEN SWITCH OFF FOR REMAINDER OF FLIGHT. BOTH CAUTION LIGHTS REMAINED ILLUMINATED. MAINTENANCE INSPECTED AND FOUND NR 2 ENGINE DC STARTER/GENERATOR FAILED INTERNALLY. REMOVED NR 2 ENGINE STARTER AND REPLACED WITH NEW PART FROM STOCK IAW MTC 6243101. OPS CHECK OF STARTER AND DC 28V GENERATION SYSTEM GOOD. AIRCRAFT RETURNED TO SERVICE.