I recently got a Bachmann 35 ton two truck Shay. Beautiful engine, didn't run right out of the box. Three of the four gear were loose, which probably caused that. It's such a nice engine, I would like to replace the current rucks with the new die cast #88999. How difficult is this? I have installe a sound system in one of my other steam locos, so i am at least somewhat tecnically adept. Any helpful hints would be appreciated. Peter J.