I just bought a junk box of SM parts, and some were rusty faceplates, rear cover plates, etc. 1st I bought a bottle of Coke, which I haven't done in years, the BIG bottle in case it worked. I poured some in a stainless steel container. I took the parts outs and brushed with a brass brush occasionally to loosed it up. I wasn't really sure it was doing much. Then I rinsed them down and stuck 'em in white vinegar, that seemed to actually work pretty well for me. Now I'll take some to work tomorrow where I have access to a full size buffing wheel, that does a great job without leaving marks.