It has been known for some to put a sleeve over the bolt to take up some of the slack in the worn hole. That sleeve may have welded itself to the bolt. And yes it is common for the bolt to be bent. Most go with a larger bolt after a
refit. 5/8", If I remember right?
It's also been known to cut the keel trunk to get the bolt out, as you suggested. And then to reinforce the new pivot on the
repair.
If you can get one of those diamond coated wire blades and have the room to go up the side between the trunk and keel, you could see-saw the bolt thru on both sides then drop the keel. It's probably seized in the keel iron.
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