So I recently bought this Cannondale multisport 500, the original owner raised the stem way too high for my taste. As seen, I've already removed the screw at the top of the stem. But when i try to push down or pull up the stem, it won't budge. I think that black piece is an extender? I need help on removing that. I think it might be rusted on the inside but I'm not so sure. Anyone with any opinion, feel free to give me some heads up! Thanks.