I still didn't get a chance to take pics of mine, so I'll use yours.
On the collar was one pair of recesses shallower than the other? All I really had to do on mine was pull the cotter pin, rotate the collar 90 degrees and reinsert the cotter pin using the shallower set of indents on the collar. The pin was quite snug and the plate became virtually wobble free. It is possible that my cotter pin was a slightly larger diameter as well, it is hard to tell from the pics.
Oh, and mine is a Corona knockoff branded "Victoria" but I hear they are made in the same factory.
My collar notches looked the same and the cotter pin on mine was so mangled, that I could get the collar to rotate anyway. That's why I went with the JB weld/bolt...
Either way, my reading has found that that is the one thing that is probably the most important tweak for the corona owner in brewing, to make sure that the grinding plate is not wobbly on the shaft. SO if you're lucky enough to be able to do it without tearing it apart that's probably the preferable way. But if not, a bolt, JB weld, or some other means will work just as well.