I ordered this motor as it was described as being robust compared to another similar model. The first problem was that the polarity was reversed, so the extension and retraction was reversed, which I can't work with. However, the engine burns out when you try to lift the trailer. Bad quality and waste of time. I have lubricated all the gears and replaced the gearbox and the engine runs fine with no load so I believe the problem is with the engine and not the chassis or gearbox.