As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
AIRCRAFT WAS GROUNDED: AT FL 370 1 TO 15 MINUTES INTO FLIGHT CABIN PSI BEGAN FLUCTUATING +/- 700 FPM SYSTEM #1 CONTROLLER. DESCENDED TO FL 350 +500/-700 FPM V/S DESCENDED TO FL290 - STABILIZED TO FL 290 - STABILIZED CABIN ALTITUDE / FOR SHORT PERIOD. REPLACED CABIN ALTITUDE PRESSURE SWITCH AND ACCOMPLISHED A SATISFACTORY OPERATIONAL CHECK PER AMM 52-73-12, 52-73-00-720-003-A AND AMM 34-22-25-790-001-A.