What was found
PHL-FLIGHT#3907. CREW REPORTED ALL GEAR DOORS CYCLED OPEN AND CLOSED 4 TIMES AFTER GEAR WAS SELECTED DOWN AND LOCKED. MAINTENANCE OPERATIONALLY CHECKED PROXIMITY SENSOR ELECTRONICS UNIT(PSEU), OPERATIONAL CHECKED GOOD. AIRCRAFT GROUND RAN, AND DOORS CYCLED. PROBLEM COULD NOT BE DUPLICATED. AIRCRAFT RETURNED TO SERVICE. PIT-FLIGHT#3891. CREW REPORTED GEAR DOORS CYCLED OPEN AND CLOSED SEVERAL TIMES WHILE ON APPROACH. MAINTENANCE REPLACED RELAYS 3261-K8 AND 3261-K9. GEAR SWUNG SEVERAL TIMES, WITH NO DEFECTS NOTED. AIRCRAFT RETURNED TO SERVICE.