One side of my swamp cooler isn't spinning right, it's like it's spinning the "whole thing" instead of just the shaft inside. I presume that it's a "seized bearing" on that side. But in trying to remove the old bearing off the shaft, there's a reason the whole thing is spinning, it's really seized on hard. How to get off a very stuck one?
Most common answers I've seen from around the interwebs: use a "pulley puller" (aka "jaw puller" -- you can rent them from your local auto store for free) tried it, it removed the bearing but didn't remove the small copper core. Which of course must be removed. Might work if it's not seized entirely. You can even buy a small pulley puller from home depot, but it works great on pulleys, not so much on bearings.
Some people have luck with using penetrating oil. Didn't seem to be enough in my case (gravity isn't working in favor of the penetrating oil maybe). For some it works. Maybe theirs isn't seized on totally.
Some recommend using heat. Didn't try that.
I did it the old fashioned way, with a hacksaw. Remove any collar with a hex screw. Carefully cut a groove in the bearing all the way down but trying not to cut into the shaft. Use a screwdriver every so often to pry and see if you've cut it through enough. After cutting, the two sides can be pried apart. Clean with "fine wet sand paper" or "emery cloth."
Other ideas: cutting torch, angle grinder.