As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
FLIGHT 751 MIA TO MEX CREW REPORTED, PRESSURIZATION WOULD NOT LEVEL OFF ON CLIMBOUT, JETTISONED FUEL BELOW LANDING WEIGHT. AIRCRAFT RETURNED TO MIA AND LANDED WITHOUT FURTHER INCIDENT. MAINTENANCE FOUND FLOW CONTROL VALVE NOT OPERATING PROPERLY. REMOVED AND REPLACED LT & RT FLOW CONTROL, SHUT-OFF VALVES, RT HP REGULATOR & NR 1 8TH STAGE CHECK VALVE. OPERATIONAL NORMAL IN ACCORDANCE WITH MM 36-10-21 & MM 71-00. AIRCRAFT RETURNED TO SERVICE.