Well i am getting ready to sell my old daily driver which is a 94 pontiac bonneville and i am fixing little things to sell the car. Anyways...so the car has been sitting for a few months and i went to move the car and the passenger rear wheel was locked up. No problem.... i rocked it back and forth and it broke loose. I then took the drum off and spray everything with brake cleaner and hit the shoes(plenty of life left in them) and inside of the drum with some light sand paper to remove any surface rust. But that didnt fix the problem, once i apply a little more than light brake pressure that wheel locks up, but unlocks when i accelerate. I am thinking it may be the wheel cylinder but i am not too sure. Anyone have any ideas what it could be?