I took the flywheel off my Tecumseh lawn mower today because the kill switch wasn't working right and it's under the flywheel. I took off the nut, pried up on the flywheel, and rapped on the end of the shaft a couple of times and it popped off. Just like it's supposed to. Later I went to put it back together and the nut wouldn't fit. I had messed up the end of the shaft by hitting it with a steel hammer. Then I messed up the nut trying to get it to start anyway.
I don't think I can straighten it up with a triangle file, and all my dies and most of my taps are metric, so tomorrow I gotta figure out what size threads they are from the nut and buy a die for it -- and hope I can chase the threads. (looks about like 7/16" fine thread)
Now here's the really stupid part: I had a 7 pound block of lead just sitting on my workbench that I could have used instead of the hammer. I nice beer-can sized cylinder that would have made a terrific dead-blow hammer. (Also I should have put the nut loosely back on before I hammered on it so I could use the nut to chase the threads if I messed them up a little. Might not have worked though, cuz the shaft seems to be harder than the nut)
Just putting a penny on the end of the shaft before hitting it with the hammer probably would have been enough to keep from damaging it.
Dumb, dumb, dumb...
Bob