There is a product called marvelous mystery oil. It's sold in auto parts stores. Try soaking it in that. The problem is that the bare wear points of the aluminum corrode, the mystery oil can remove some surface corrosion. Shouldn't take long. Maybe an hour. I would soak it for 15min and then try and move it by hand. Then repeat.

Some other products may work too, that was just the first one that. And to mind.