What was found
CREW REPORTED PRESSURIZATION CLIMBING AT 2,100 FT, LEVELED 6,000 FT AND CABIN PRESSURE REMAINED 4,800 FT. ATTEMPTED MANUAL MODE UNSUCCESSFULLY. CREW RETURNED TO FIELD AND LANDED WITHOUT INCIDENT. ARRIVAL AT GATE, FOUND AFT CARGO DOOR NOT FULLY CLOSED. AFT EDGE OF DOOR OPEN APPROXIMATELY 1 INCH. MAINTENANCE INSPECTED, FOUND DEBRIS, DIRT IN DOOR TRACK, CLEANED AND LUBED AFT CARGO DOOR TRACKS AND PERFORMED CHECKS IAW AMM. ACFT RELEASED FOR SERVICE.