I have this same locomotive, and love it. I've also been in it a couple times. I would make sure that the screw on the bottom of the driver set is tight, and well as take the boiler off and make sure the motor bracket screws are tight and the motor is properly engaging with the axles. Just a little off and it'll bid and or chew up the gears. Mine has so many hours on it the gears are visibly worn.