I've been asked to post some photos and a description of the trim ring refurbishing so far.
1. Grind a "V" into a pair of Channellocks. This will leave a wedge to get under the pinch seam.
2. Pry open the pinch not quite to 90 degrees.
3. Pull the two halves apart.
4. With a 1/4" thick piece of steel clamped vertical in my vise, it served as the "dolly" for the normal hammer and dolly method to get the dents out of the face. Even a piece of wood or hard plastic would work. The flat surface can be worked pretty good but still won't be perfect unless you have a ton of experience.
5. At this point, a Dual Action sander was used with 80 grit paper, make sure you keep the pad flat with the flat face of the trim ring. This will give a flat surface all the way around. You might notice spots that aren't getting sanded, they are low and can be hammered out some more.
6. Switch to 180 grit, then 220 grit.
7. A regular sanding block with progressively finer paper is used to remove the previous sanding marks. Go until it can be polished with a normal cotton polishing wheel. Rouge will bring out the shine.
8. Metal polish like Wenol will make it pop.
9. For the brushed inner part, some are nice enough to use a coarse Scotch Brite by hand, others take a piece of 180 grit paper. Just follow the factory brushed pattern.
10. Assemble the two halves back together.
11. Hammer and dolly the pinch seam. A section of 2x4 in a vise will give a soft enough surface to just catch the edge of the trim ring to hammer it back together.
It's a lot of work but it really didn't cost me any money, it was stuff that was already laying around.
Photo #1 shows the modification to the Channellocks.