I just picked up a G-scale 4-6-0 (Super Chief) at a local train show. The Gear axle has split and the wheels pull out, derailing the train. I'm just trying to replace that one gear to see if I can get it back on the tracks! I found a guy on Facebook (search for Jiro Yeramian) who says he can make the gears for a price, but I want to try and fix it myself first.

Have you opened yours up to see what's wrong with it?