Hi Folks,
I'd figured I share this because it has been very helpful for me. I bought 4 secondhand O27 switches where the tinplating was completely worn off of the rails. From the way the plating is absent, it appears it wasn't from normal wear but rather a deliberate, repeated polishing with an abrasive pad or Dremel-type disk. The sparks on the control rails when any wheelset made the electrical connection for the non-derailing feature were quite bright, and even WD-40 did little to reduce the sparking. But the Rail Zip is like magic!
Not only are the sparks almost completely gone, the surface is very smooth now. I would say the best technique is to apply it with a Q-tip very sparingly, let it sit overnight, then wipe it off completely, followed by another wipe with something like Windex. What a difference!
Hope this helps! Joe.