Replying to Glidecam screw replacement

So this Sunday, I'm planning on picking up a 2000 Pro from a guy in my city. Hes selling it for $75 because he doesn't have a camera anymore and doesn't have any use for it (and i dont think he knows what he could be getting on Ebay). He said that its in perfect condition other than 1 screw that secures the top plate on is missing, he said it will still hold fine but I do want to replace it. Any idea is glidecam will send me one, or what thread and size I need so I can just get one at the store?