Curtis Jere Crane Lamp set screw source  

Hi all. I bought a large Curtis Jere Crane Lamp and it is missing the set screw clamp doo-hickey that locks the position on the crane arm. I've attached a web photo that shows what it looks like. It's like a ball with a baseball bat shaped arm, only a few inches long. I'd like to locate a replacement but I don't even know what keyword to search for, anyone know the official name for this type of screw clamp? Or better yet, have one they don't need? (I can dream . . .)