What was found
UPON GEAR RETRACTION, LT MAIN GEAR INDICATION WAS AMBER CROSS HATCHED THEN RED CROSS HATCHED AND STAYED THAT WAY. GEAR SOUNDED TO HAVE RETRACTED NORMALLY. FOLLOWING QRH DID NOT FIX THE PROBLEM. UNEVENTFUL LANDING FOLLOWED. HYD RESS WAS NORMAL. RECEIVED 3 GREEN DOWN INDICATIONS. REMOVED AND REPLACED LT FWD AND AFT UPLOCK PROXIMITY SWITCHES. WORK DONE IAW MM 32-10-11 AND CMP 326020. PART SN OFF: 4AS8135500-503 SN: OFF NA SN ON: N/A PN ON: 4AS8135500-503 (AFT)