The Fine Things are Always Hand Made
So far, limited to using Turtle brand liquid chrome polish over the past 20 odd years. But then I have avoided heavily corroded items.
Vacuum first while using a modernly stiff artist brush. Use small squares of old towels, gentle pressure and change to a new piece of towel when much grit accumulates to avoid further scratching chrome.
This product works reasonable well on steel chassis. But again I have been avoiding corroded items. For the hammered look painted Zenith chassis later 1930's, using auto polish.
Another method, if you have more significant rust, and you remove some/most of the components, is to use Naval Jelly. Apply, wait, then wash it off with a lot of water and let things dry thoroughly. Repeat if needed. Then polish as Dave described.
Caveat: before restoring a really rough but relatively common chassis, just go look for a better example. There are many sets in the "above average" chrome range, many separate tuners and amps...so watching for a better unit is almost as good as a heavy handed cleaning. If its a rare set...then rechroming is best.
Thanks fellas....going the naval jelly route !
I have tried phosphoric acid (same ingredient as in naval jelly) and it dulled the chrome around the rust spots. I think if you keep it confined to just the rust spots you will do a lot better than I did. Otherwise the best I have found is to use #0000 steel wool lubricated with a chrome polish. This won't work for heavily raised rust spots, but for wide areas it is decent. It is not easy on good chrome around the rust, but it definitely improves the overall look and should only be done on poor chassis. Beyond this, I haven't found any magic way to clean the rust. I even tried aluminum foil "balls" as described in some online "tricks" to remove rust on chrome, but that was way too hard on the surrounding chrome.
I am pretty anal about cleaning chrome when I get a decent set. I remove all covers and rinse thoroughly in water and soap to remove any grit before using any wiping motion on the chrome. There is always grit that you can't see and just wiping leaves visible fine scratches in the chrome. I have see so many sets that were just wiped and you can tell instantly from the haze caused by fine scratches.