I tried a file and had no luck. something about two spinning surfaces--one that grinds and the other to keep it round. Maybe your file is better than mine. A grinder and a hand drill works too. I also tried it on the belt sander with success, but it was harder to shape. You will go through the cutoff wheels pretty quick, but they are cheap. Wear protective glasses for sure.
no locktite is necessary. If you can unscrew them, you would need vice grips or something, and it would probably ruin it. There is no way they will come lose on their own.