What was found
ON APPROACH, CREW REPORTED LT MAIN GEAR DOWN AND LOCK INDICATOR FAILED TO ILLUMINATE. COMPLIED WITH EMERGENCY GEAR EXTENSION,STILL NO DOWN LOCK INDICATION, DECLARED EMERGENCY. LANDED WITHOUT INCIDENT. MAINTENANCE ADJUSTED LEFT MAIN GEAR DOWN LOCK SWITCH. COMPLIED WITH LANDING GEAR EXTENSION AND RETRACTION SYSTEM CHECKS, CHECKS OF. AIRCRAFT RELEASED BACK TO SERVICE.