I have a ( looks very used) Arnold Repido 4 wheel trucks loco. Looks like the company went out of business a long time ago. Or maybe split up? Pulling 12 cars with it seems to act like it might be putting a strain on it. And this is flat track, no hills yet. Do you think its just getting old and worn out or is this normal? Also, what is the advantage of using a loco with 6 wheel trucks? Is it more powerful? or is it just for looks?