I belive there is a switch on the bottom of the locomotive that locks the electronic e unit in forward or reverse. II'm not completely sure on this. One switch turns the smoke unit on and off and the other is for the e unit. Play with those and that might just fix it. ( just remember to not run the smoke unit without fluid) . Also oil the axials, and side rods, and gears. Just a little bit. Clean the wheels and pick up rollers. Don't get oil n the underside of the wheels. I only use motor oil on my trains now. Also check for hair etc stuck on the gears, wheels. A picture of the bottom might be helpful. Keep us posted. It might be a simple fix!