Take the "open" door apart to figure out what needs to be done to the other door. You need to take it apart sooner or later to "refreshen" it and properly lubricate it anyway. It may be that the door itself is stuck or jammed into the opening too. May need to crawl inside and use your feet against the door as persuasion too,
Scott

Scott Ward

2 1948 1.5-ton Loadmasters
The red one and The snow pusher
1 1950 3100
1 1955.1 Chevy 6500
1 1954 Chevy 6500 2-Ton
1 1955 1st Series COE 5700
1 1963 K20 (454)
1 1964 C10 (350)
1 1951 1.5-ton Dump Truck
1953 and a 1956 Ford F800

Raising a teenager is like trying to nail Jello to a tree!