As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
AIRCRAFT WAS GROUNDED. AT CRUISE FL 360 SYSTEM 1 CABIN PRESSURE VS ERRATIC AND CABIN ALT 8850 FT FLASHING GREEN, DESCENDED TO FL 320 CABIN ALT RETURNED TO NORMAL AND 7500 FT STEADY VS AND ALT. REPLACED NR 1 CABIN PRESSURE CONTROLLER AND ACCOMPLISHED A SATISFACTORY OPERATIONAL CHECK, PER AMM 21-31-34.