Hi Boots,
Last couple of these I think sold for $600 and $1200. As Steevsee mentioned the hologram does fade. I had a Gunsmoke I was repairing for another collector and the hologram was faded but still good enough to play the game. It is one of the central parts of the game so if this is damaged the game would be worth next to nothing. I know of 2 holograms which were damaged due to cleaning. If you use water or any other liquid the hologram will just rub off the drum. Most of the other repairs involved, cleaning steppers, rewinding a coil, replacing few relays, etc. Game is designed for easy access to the major assemblies. Great EM game to play once it is all working. I have some notes and photos of the one I worked on if you need a hand.
regards Derek