I am very new to model train repairs, I thank you for any help in advance. I rewired my transformer and stop switch. I get a good voltage all around my track, 17.5V at maximum. Issue I am having is with a locomotive. It ran at first, after it was in attic for about 15 years. I oiled gears and cleaned out the smoker. Now its creating a short when I place it on a track. Are there any suggestions on what I should be looking at first? I already took it a part and inspected for any damaged wiring, I just dont see anything out of place.