As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
FLT 722 FROM TOL TO CLT. LEFT MAIN GEAR DOOR LIGHT REMAINED ON AFTER GEAR RETRACTION ON TAKEOFF. RECYCLED GEAR CYCLE PER AOM PROCEDURES WITH NO HELP, LIGHT REMAIN ON. AIR TURNBACK TO TOL AND LANDED WITHOUT ANY INCIDENT. INVESTIGATION FOUND THE MLG DOOR SWITCH LOOSE. CLEANED, TIGHTENED MLG DOOR SWITCH AND PERFORMED OPERATIONAL SYSTEM CHECK OF LIGHT INDICATION IAW MM 32-62-0. AIRCRAFT RETURNED TO SERVICE.