First off, Welcome (your first post).
Generally a used pit goes for about 1/2 the price of a new one IF it has all the parts, no dents scrapes or broken parts and everything functions. Anything that isn't right detracts from the price..Make sure you take it apart and examine everything inside. The inside may give you a better idea on how it was maintained. Remember, there is NO warranty of any kind. Any problem will be yours to deal with. As for the controls or any other questions, you can contact the company with the S/N and ask. It will give you the opportunity to ask questions that may arise.