As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
FLIGHT 2072 - PILOT REPORTED THAT THE MAIN LANDING GEAR WOULD NOT RETRACT. THE AIRCRAFT RETURNED AND LANDED AT IAH WHERE MAINTENANCE REMOVED AND REPLACED THE LEFT MAIN LANDING GEAR UPLOCK BOX. THE LANDING GEAR EXTENSION AND RETRACTION SYSTEM WAS OPERATIONALLY TESTED GOOD AND THE AIRCRAFT RETURNED TO SERVICE.