2 5/8" ball hard to release

Yes double check the size. It should be stamped on the ball and the tongue. With age mine works better at first I had issues with unlatching as well as the ball dropping out. In time we have learned the release point for the latch. Early on we would sometimes raise the truck 6 inches before it would drop or have to put the truck in drive or reverse to get it to drop but now it seams to slip out easier.

Think about it, when you back into a site the ball is pushed back and when you use a pull through the ball is pulled forward agains the tongue so there is tension.