What was found
AIRCRAFT WAS GROUNDED: AFTER SELECTING FLAPS 30 ON LANDING, LEADING EDGE TRANSIT LIGHT STAYED ILLUMINATED. EXECUTED A GO AROUND AND RAN THE QUICK REFERENCE HANDBOOK PROCEDURE. LANDED AT FLAPS 15 WITH LEADING EDGE TRANSIT LIGHT ON. LEADING EDGE TRANSIT LIGHT STAYED ON THROUGHOUT POST GO AROUND AND SUBSEQUENT LANDING. REMOVED AND REPLACED LEADING EDGE FLAP RETRACT SENSOR 3 PER AMM 27-88-11.