AntiqueSledMan, yep they're all like that. That one is the worst one, but they've all been ground on with a Dremel. Funny thing is, the bolt doesn't really fit into the "slots". It's too wide.
I got a note from Walt Kirst today, he basically said it would be more trouble than it's worth, and recommends a new cylinder. So I literally don't have anything to lose by trying to fix this one. It needs a new one anyway, so I'm going to mess with it and see what I can do. Worst case, I ruin it further and have to replace it. I'm at that point anyway.
Here's my plan of attack.
Tomorrow I'm going to go to the hardware store, and get a bolt that fits the arbor hole closely. I'll get one with a tapered head, so it will center in the hole. I'm then going to chuck the bolt in my drill press and use a file to remove as much of the offending area as I safely can. There's a lot of meat on that portion of the cylinder. So I'm hoping that I can remove quite a bit of the slots. Then I'll work each slot by hand, with files and try to restore them. If it works, great. If not, I'll get a new one. At this point, I have noting to lose.