i like to take the wheel off and beat on the drum. when you beat on it you are not just pounding,
the idea is to get a rhythm going. try to make it ring (like a bell, sort of) it is the vibrations that break things loose.
i learned this from an old gunnery Sargent, this is how we got large props to break free. a brass hammer works best, but
steel will do. this works on many things. use it all the time on case bolts/ screws when working on motorcycles.
and is how i always get drums that have been sitting for years apart.