OK, just watched a youtube video, no screw!
I wonder if it's possible that the bearing carrier could have split and let a roller fall out to get caught between the drum and the base?
The shaft seems to be removed by inserting a winch handle and rotating to free the pawls while lifting.
Could that prevent the drum from lifting if done inadvertently beforehand?
Maybe I'd try spinning a winch handle both ways while keeping upward pressure on the drum to start with.
Or turning/lifting the drum while tapping it with a piece of soft wood to dislodge whatever small part may have come adrift.
Or pulling up sharply on some pieces of rope
tied tightly around the drum - the slide hammer effect.
Obviously take steps to prevent small parts
flying out/overboard whatever you do.
Good luck with it!