What was found
MAIN CABIN DOOR JAMMED PARTLY CLOSED. GATE AGENT REPORTS DOOR IS SLIGHTLY TILTED TO ONE SIDE. REMOVED FROM SERVICE. UPON ARRIVAL AT A/C FOUND MCD DOOR WOULD NOT CLOSE. DOOR WAS NOT IN LINE WITH FUSELAGE. LOOSEN CHAINS AS REQ TO CLOSE MCD IAW AMM 52-11-00-820-003-A. 27752 SECURED MCD IN CLOSED POSITION & PLACARDED AS DO NOT OPERATE, & VERIFIED MCD INDICATES CLOSED & LOCKED. SECURED SUPPORT ARM HOOK MECHANISM CONNECTING ROD IN A SECURE MANNER. FOUND MAIN DOOR TWIN CHAIN ASSY OUT OF ADJUST ON SUPPORT ARM. ADJUSTED TWIN CHAIN ON DOOR SUPPORT ARM IAW AMM 52-11-00-820-804-A, SUBTASK 820-059-A. OPS CHECKED GOOD IAW AMM 52-11-00--820-801-A. NO DEFECTS NOTED.