As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
DURING CLIMB OUT AT CPR ON FLIGHT NR 8788 THE PILOT NOTICED THAT THE CABIN WAS NOT PRESSURIZING AT 1000 FT. THE CREW RECEIVED THE MASTER WARNING. THE CREW ELECTED TO RETURN TO DEPARTURE. NO EMERGENCY WAS DECLARED. THE AIRCRAFT LANDED WITHOUT INCIDENT. (K)