i just bought a new "Bachmann HO Chattanooga" Train set. Everything ran smoothly. Then I decided to switch out the plastic wheels for metal ones on all my cars. Now the locomotive wheels will spin but cannot pull the load. I would like to know if my 0-6-0 steam locomotive is too small to pull many cars or if it has something to do with the metal wheels. Also, if I need a bigger locomotive, does anyone have any ideas for a good one? with dcc included???Thanks. And Hello to everyone in the site.