I have a good friend who is a professional mechanic and he strongly recommends that one never buy a used lift other than one reconditioned and sold by the OEM with their backing; and that any new lift be installed by the company that builds it. You're talking life safety issues here, and that is not something that should be left to chance. You're not going to fare well trying to catch a falling vehicle. No skin off my nose either way, just passing along advice I have been given by a pro.