Floyd posted a link to some suggestions on getting the mechanism off. I did mine 6 years ago so I'd have to look closely at the mechanism again to remember exactly what I did.

I know there are some raised sections on the mast that prevent the mechanism from being removed. I think I just pried on the mechanism with a screw driver where the raised areas made contact. Once the mechanism was pushed over the raised sections, I was able to tap it off with a rubber hammer.

Now that I think about it, I might have reinstalled the mechanism onto the replated mast BEFORE repainting it. I might have masked off one end of the shaft, slid the mechanism to that side, repainted it and then removed the masking. Don't remember exactly any more.