Bumping this thread because i recently experimented with White Vinegar and Peroxide.
It actually does work but the smell can be unpleasant.
Mixing a small amount of 50/50 percent into a small glass jar with top and throw the parts in the mixture re seal it shake it from time to time and it works in a few days in the jar.
Or outside the jar, brush the brass with the mixture and letting it fully dry between coats sometimes it takes several coats.
