What was found
LOST CABIN PRESSURIZATION AT APPROXIMATELY 16,000 FT, DEPRESSURIZED TO 10,000. CABIN WOULD NOT PRESSURIZE IN EITHER AUTO OR MANUAL MODE. RETURNED TO SLC. REMOVED AND REPLACED CARGO DOOR SEAL IAW MM 52-30-00. PRESSURIZED AIRCRAFT TO 3 PSID. LEAK AND OPS CHECKS GOOD.