As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
LAS/LAX - FLT 707 - DURING TAKEOFF/CLIMB, AIRCRAFT WAS UNABLE TO BE PRESSURIZED. CREW RETURNED AIRCRAFT TO LAS AND LANDED WITHOUT FURTHER INCIDENT. MAINTENANCE FOUND FORWARD OUTFLOW VALVE INOPERATIVE. REMOVED AND REPLACED FORWARD OUTFLOW VALVE. AIRCRAFT RETURNED TO SERVICE. (X)