The radial finish is not simply brushing - it's applied using a lapping machine. I took this video of how it's done at the Omega service center in NJ while there for training some time ago, so it will give you an idea of what is involved:
One thing to consider is that it tends to remove a fair bit of material, and some cases (Mk. II Speedmasters for example) end up losing a lot when the wrong person does this. There are watchmakers here who do this, but unclear if they would do it just on it's own or not. I'm sure one will likely pop in and offer his services...
Note it's a Dynamic case that he's refinishing in the video...
Click to expand...