What was found
DURING DESCENT INTO MSP, LOST CABN PRESSURE AT APPROXIMATELY 36,000 FEET AND MASKS DEPLOYED. CABIN PRESSURE WAS RESTORED MANUALLY, AT APPROXIMATELY 6,000 FEET, CABIN PRESSURE WAS LOST AGAIN. FLIGHT CONTINUED INTO MSP AND LANDED WITHOUT INCIDENT. MAINTENANCE REPLACED THE OUTFLOW VALVE GEARBOX AND BUTTERFLY VALVE. MASKS WERE RESET. OPERATIONAL CHECK OK.