Sounds to me like the catch and the lock mechanism needs cleaning. Maybe the rods need to be adjusted. Especially when cold, the old grease hardens up and can make it a PITA to open. Here's a way to check the alignment. Look at the catch and bolt when closing the door slowly. If the door or bolt isn't adjusted correctly, the bolt might hit the metal of the door. It should be hitting in the center of the catch. But I still think the catch is dirty and needs cleaning. Mine catch sometimes doesn't close and it bounced off the bolt. Need to clean my catch.