I have a 70s SG Custom (3 pickup) which I am guily of neglecting for several years. When I finally pulled it out of the case, it had developed tarnish and gunk all over. I painstakingly cleaned it off end to end, and then had it set up. I had forgotten what a great guitar it is. Now I have discovered that the crud is coming back. There are many places where the gold is worn away, so there is a bunch of exposed raw metal. My sense is that air hitting that metal is the cause of the problem. I have actually tried to hunt down a place that will re-plate the metal, but I haven't found any. Even if I had, the cost would no doubt be prohibitive. So I am falling back to spraying some kind of sealer on the bare metal in order to keep this from happening. I just need to know what to use. Anybody ?