What was found
DFW - CREW REPORTED A LOUD BANG IN THE FORWARD FUSELAGE AREA FOLLOWED BY ERRATIC PRESSURIZATION CONTROL. EMERGENCY DECLARED RETURNED DFW LANDED WITHOUT INCIDENT. AIRCRAFT REMOVED FROM SERVICE. FOUND THAT THE FORWARD EDGE OF THE PASSENGER ENTRANCE STAIRS DOOR BELOW THE LEFT NUMBER 1 DOOR WAS STICKING OUT DUE TO A BROKEN CLEVIS THAT CONNECTS THE DOOR TO THE LATCHING MECHANISM. REPLACED FORWARD CLEVIS BRACKET. SYSTEM GROUND CHECKED NORMAL OPERATION.