Geof says:

Thad,

You can use a rubber ink eraser to clean your track (that’s what I use). Some people use Goo Be Gone (a cleaner) by dampening a lint free cloth and wiping the top of the rails. Be careful to wipe the rails dry once they are clean because any residue of Goo could make the wheels on your locos slip.

You should also clean the electrical ‘pick-up’ wheels on your locos by using either of the above methods. If you can possibly mount your locos upside down in some sort of cradle (I line a small box with cloth or foam to protect and hold the engine) and then attach power so the wheels turn. Gently apply the cleaner or eraser and let the turning wheels scrub themselves. Note that your steam locos probably have some or all the pick-up wheels on the tender, so you’ll have to turn them by hand.

Finally, you can purchase a track cleaning car which, depending on the manufacturer, will do the above while you run your train. The downside to this method is that your trains have to be running in order to use the track cleaning car so it is best suited as a regular ‘weekly’ maintenance tool.

On a interesting side note, if your track is nickel silver (and it probably is if you are running N or HO gauge), the oxide of this metal compound is a BETTER electrical conductor than the metal rail itself!