I assume you found out from the seller that the valves to go up and down and not stuck? Could be a spring issue or the felts, pads, corks or whatever are different from the others, an alignment problem. No rust that I know of. Exposed slides can get corroded, turn green, etc. Hard to see if there are problems inside the tubing. Check it over when you get it and let us know what you see the problems to be.