As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
MDW-LAS - FLT 403 - DURING CLIMB THE LEFT MAIN GEAR UNSAFE LIGHT ILLUMINATED WITH THE HANDLE IN THE UP POSITION. HANDLE WAS RECYCLED WITH THE SAME RESULT. CREW ELECTED TO RETURN TO MDW AND LANDED WITHOUT FURTHER INCIDENT. OVERWEIGHT INSPECTION WAS NOT REQUIRED. MAINTENANCE REPLACED THE LT UPLOCK SENSOR AND UPLOCK GEAR CARD. OPS TEST NORMAL PER BMM 32-61-00, PAGE 107. (M)