Plain brass will oxidize fairly quickly, whether operated or not.? Same with brass rail.? Back in the day we used a product called No-Ox, which was one brand of electronic contact cleaner, and it made a big difference.? I've heard of folks recently using ATF fluid.? Annecdotally, the product Rail-Zip is ATF fluid in a small bottle marketed to us train guys.? Assuming all surfaces are clean, there should be no detectable difference in current transmission among any of the commonly-used metals - brass, NS, copper, even steel.? As an earlier poster noted, there might be an issue with the motor itself - maybe a short in the armature that's causing a big draw??

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DM