Wow!
Sounds like you're having a hell of a time looking for the "sweet spot", even "beating it in pretty much all the spots", wacking it "over and over". Of course like was already mentioned "sounds like you have a hard one".
Some of the advice is pretty good I guess, pure force seems to be the most popular solution, "hit it like you mean it" Hell one guy even said he "beat on one till exhaustion", another guy, "beat (his) for days... broke so I didn't have any real good places to hit it either"! Sounds a bit extreme to me.
Some of the advice is focussed on your technique though, "side to side also works", "soak it", use "oil". In fact the one suggestion, "wedge into the slit" is usually what I try to do, every once in a while though it is pretty cool to "put some stank on it" if you can!
Whatever you do brother DO NOT LISTEN TO Blazinzuk, "Try all the suggestions above and then if they don't work get some good cut off wheels for your grinder and have fun

"
It just ain't worth it!