As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
PHL - FLT 973 - FLIGHT RETURNED TO FIELD AT PHL DUE TO A LEFT MAIN LANDING GEAR UNSAFE LIGHT INDICATION. FLIGHT LANDED WITHOUT FURTHER INCIDENT. AN EMERGENCY WAS DECLARED. MAINTENANCE REMOVED AND REPLACED THE 'LEFT GEAR UP AND LOCK SWITCH' PRINTED CIRCUIT CARD M988 PER THE MM. OPERATIONAL CHECK GOOD. (M)