What was found
(CAN) DURING CRUISE CABIN STARTED TO CLIMB AT A MODERATELY RAPID RATE. AFT CARGO DOOR SEAL WAS REPLACED. IN A LATER FLIGHT THE SAME PROBLEM RETURNED WHILE PASSING THROUGH FL70. CABIN CLIMBED AT A RATE OF 3000FT/MIN AND DIFF WAS ZERO. ENGINEERS FOUND FORWARD PAX DOOR SEAL AND AFT BAGGAGE DOOR SEAL OPERATION ERRATIC. LEAK WAS TRACED TO A LOOSE UNION AT THE RESERVOIR. UNION TIGHTENED AND PRESSURE RUNS COMPLETED WITH NO FURTHER DEFECTS.