Hi Evo,
Sadly electroplating when left in the elements will break down rather quickly, especially the production style plating which doesn't have much copper applied as the base coat prior putting into the Nickel bath which builds up the plating thickness and base metal protection.
If you left the parts in the nickel bath as long as we used to do you'd go broke within a month.
I've seen some members here use scrunched up ally foil and water and rub it back and forth which is quite a long process, but some of the results are fabulous. I will say though that is not a long term answer as the areas where the plating has broken are exposed to the atmosphere and will continue to corrode as is the current state of the bars.
The only way to overcome the corrosive process is to totally chemically strip the old plating and then start the plating process all over again and thus seal the base metal. (alternatively paint) One thing I will say though is that this treatment is not as cheap as it used to be back in the 1970's when there were plating shops in every industrial complex. Now there are only a small handful of them left and this is due to the massive EPA regulations that govern this industry over the top, thus most of the plating is now done overseas in countries where they continue to be able to pollute the planet to no end.
Cheers,
BB.
