What was found
BOS - FLT 2673 - AFTER TAKEOFF, WHEN LANDING GEAR WAS RETRACTED, THE RIGHT MAIN LANDING GEAR UNSAFE LIGHT ILLUMINATED AND STAYED ON. CAPT RECYCLED THE GEAR BUT THE LIGHT REMAINED ILLUMINATED. FLIGHT RETURNED TO FIELD AT BOS AND LANDED WITHOUT FURTHER INCIDENT. NO EMERGENCY WAS DECLARED. MAINTENANCE REMOVED AND REPLACED THE RIGHT MAIN LANDING GEAR UPLOCK SENSOR PER BOEING MM 32-61-21. ACCOMPLISHED GEAR SWING. OPERATIONAL CHECK OF GEAR SYSTEM GOOD. (M)