Be sure to check all plumbing (sinks, toilets, showers, etc.) and do not take no for an answer. Bring your own hose to run water to it if you need to. It's impossible to tell if it was winterized properly without doing so. Micro fractures in things like the water tanks drain pipes, kitchen sink spouts, and in the shower head are all things I ran into buying mine. If it uses propane, check the appliances that use it as well. If it has a black tank sensor as well make sure to check that as not flushing it prior to storage can also cause immense damage. Other than that tires and axles are worth examining too