What was found
CLIMBING OUT, AROUND 12,500 HAD THE MASTER CAUTION ILLUMINATE DUE TO NR 1 ENGINE SOURCE OFF LIGHT. THE DRIVE LIGHT ALSO ILLUMINATED AND COMPLETED THE CHECKLIST WHICH INCLUDED DISCONNECTING THE GENERATOR DRIVE. RETURNED TO DEPARTURE. R & R NR 1 IDG REF MM 24-11-11-000-801 AND MM 24-11-11-400-801. PERFORMED TEST 3A IDLE POWER LEAK CHECK REF TASK 71-00-00-700-801-F00, NO LEAKS NOTED. PERFORMED OPS TEST FOR NR 1 IDG TASK 24-11-00-700-802. ALL INDICATIONS NORMAL.