Thank you for all the suggestions. We figured out that the chain may have broken because we opened the slider when it was still hitched to the truck, so it was not level and this may have put stress on the chains. The slider moves slowly but is working. Repairs cost us $800. The shop said the engine for slider was slow and recommending replacement but they could not find any engine to match. So we are using as is. It does work just slowly but we are thinking based on other comments that this is the way to works. Thanks for the comment on not adding much weight to the slide out section. We have begun to do the same and never open the slider unless the trailer is level first.