Maintenance is a major part of a tow bar. Of course, the "right" lubrication is also important.
Maybe someone needs to suggest: Chock the tires on toad, or put in gear (if auto) or pull emerg brake if manual AND release tension on tow bar before trying to unhook? Sometimes just turning the steering wheel a little to the right or left will help. I find that having the toad lined up straight behind the motorhome and on most level surface helps a LOT.
Gee, ask me how I know all this? Some kind camper helped me out.