What was found
FLT 1942 - CLT-BUF - CABIN PRESSURE - EN ROUTE FROM CLT TO BUF, AT FL370, CREW RECEIVED CABIN ALTITUDE WARNING HORN. CABIN INDICATED MORE THAN 9,000 FEET AND DIFFERENTIAL PRESSURE OF 6.2. STARTED DESCENT TO LOWER ALTITUDE. AT IDLE POWER, CABIN RATE INCREASED. PLACED PACKS ON HIGH AND CABIN CONTROL WAS REGAINED. SYSTEM NEVER ACHIEVED MAXIMUM DIFFERENTIAL. FLIGHT CONTINUED AND LANDED WITHOUT FURTHER INCIDENT AT BUF. MAINTENANCE FOUND THE FORWARD OUTFLOW VALVE INOPERATIVE. REMOVED AND REPLACED FORWARD OUTFLOW VALVE IAW AMM TASK 21-43-11-404-008. OPERATIONAL CHECK GOOD.