Okay, that helps Ed. Is there any chance that the former owner knows if it was used in a router table? If it was and stayed upside down for a while then I'm betting on sawdust has frozen the tubes in place. You are aware of the column lock aren't you? Just to make sure.
I'll also pm Harry Sinclair down in Oz. Harry is probably the person most familiar with 3612s on this forum. We'll see if he might have some ideas.
Someone I consider a master woodworker once told me that a master woodworker is not someone who never makes mistakes. He is someone who is able to cover them up so that no one can tell.