The which rail is positive and which rail is negative and which way a loco moves rule MUST be obeyed to avoid confusion. This is a basic standard in two rail model railroading. It eliminates all guesswork. It cannot be poo-pooed. I have 50 year-old locomotives with a "T" scratched into the top of the motor. Doug
Have seen motors installed upside down from the factory before. Does not happen very often. Have seen people draw arrows on trucks toward the end of frame. Marking the motor and frame is a good ideal. Will have to start marking mine when apart.
