ok i have an 80 watt lionel transformer, and a mth rail king engine, the engines bell keeps coming on by its self, will only shut off when i hit the horn. will not shut off or turn on with the bell button. sometimes it will not move or it creeps along at full power, or slows down , when i hit the horn it will take off or speed back up. so whats wrong? what is going bad,,,? engine or transformer?