from the last response, sounds more like a short to me. The high pitched sound is the current shorting itself. You need to look and see if anything is trading current where it shouldn't.
Is this close to a switch?
If it is, then you need to look close around the switch, as shorts occur in the most hard to find areas.
The other issue, don't use an emory board on the rail. Take a small block of wood, get a few sections of paper towel, dip the towel in 91% Iso alcohol, the rub over the rail , then take a dry towel and whip up the mess, repeat as needed, this will work well on the grime that builds and won't scratch the rail head.
As a suggestion, add feeders roughly every 6 feet or less. This will help with keeping the rails close to full power.