As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
PRESSURE AUTO FAIL LIGHT ON AT 9000 FEET STANDBY GREEN ILLUMINATED, PRESSURIZED, NONE UNDER CONTROL. WENT TO STANDBY, NO CONTROL. CABIN ALT SHOWING 40-50K. PRESSURE DIFF 6-7. CABIN RATE AT 4000 F/M. CONTROLLER IN MANUAL, WAS ABLE TO CONTROL PRESSURIZATION NORMALLY. AFTER OUTFLOW VALVE OPENED RATE 1500 F/M CLIMB. PRIOR TO OUTFLOW VALVE OPENING VALVE WAS FULLY CLOSED. FOUND OUTFLOW VALVE STICKING. REMOVED AND REPLACED OUTFLOW VALVE AND CABIN PRESSURE CONTROLLER PER MM.