Thanks as a clarification the set is a big hauler. Chattanooga Big Hauler

Thanks for all the help so far, the train is running fine, quite pleased with it. Anyway I have a rail car that is missing the wheels and axle so I see on eBay they size them as 36 or 31,which one do I need? The wheels now measure 30 cm on the inside and 36 on the high part. Can anyone help, seems so simple but I do not want to pay for something that does not fit

I removed all the screws on my #12 cab, 4-6-0 chassis and cannot get it passed the red switch on the rear. I do not want to break anything, any help. Thanks

Yup.realized it right after posting, reversed it and now all is going in the right direction polarity is not fighting itself. Again appreciate your input,a lot of us would be lost without your help.

Thank's Bill, Interesting thing I notices when I apply voltage directly to the front truck it goes in one direction and when I touch the rear wheels it goes in the opposite direction, does this sound odd to you. I did rewire the truck. And after seeing this I tried reversing the pins inside the loco to no avail.

Thanks Bill, I repaired it the best I could and it tracks perfectly, but now when I lay it on the track only once did it travel a few feet. When I test the engine with leads to the truck it runs really well; now when it's on the track  the voltage goes to zero ,any thoughts

Picked up a Big Hauler train set, it works but the pilot truck is damaged. Parts are not yet available, so I will to repair it. Can some one tell me what the top of the truck shaft looks like, seems oval,but am missing some plastic piece that goes on to top of the spring. I have the metal washer with 3 holes