As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
THE CREW REPORTED THAT PRESSURIZATION WAS RISING THROUGH 10K FT, NO OTHER INDICATIONS BESIDES CABIN ALTITUDE. THE CREW PERFORMED THE QRH BUT FOUND THE CONTROLLER TO BE ERRATIC. THE ACFT RETURNED TO DEPARTURE WHERE IT LANDED WITHOUT INCIDENT. MAINTENANCE R & R RELAYS K0124 & K0264, OPERATIONALLY TESTED WITH NO DEFECTS AND THE ACFT WAS APPROVED FOR RETURN TO SERVICE.