Pullrite Superglide Hitch Problem?

Alright...I may have overstated the hardness of the hit. But you cannot be too timid when backing in. Not hard enough to cause damage. But hard enough to get a good release of the jaw.

Another thought might be to remove the hitch plate and turn it upside down on a bench. Then lube up the pivot points well. Just be careful not to release the jaw by hand. It can catch ( and really hurt) fingers. But actuating the jaws after greasing well might loosen things up a bit for you.