Removing the outer skin by the methods you suggest would likely be the best approach... I kind of like just grinding off the rim to free the cover then carefully welding the two pieces back together.
... you could clean between the two parts and use JB weld to stick the them back together.
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Kevin, you make a lot of good points... I'm now thinking that my first idea about cutting the rim free would be the best way to go. Maybe if I can get a really clean cut, I could get the rim tig welded back on so that the heat could be controlled really well in order to avoid excess damage/warping. I'm wondering if I might be able to find someone with a lathe that could chuck up one of these caps. I'm thinking a good sharp bit could turn the rim free more cleanly than any other method.
