NavList:

Thanks Dave! I think you are right this was probably a solution to a problem that ceased to exist. It would be interesting to compare serial numbers with the one at the Smithsonian. Neither appear to have any significant wear you would expect with operational use. One thing that occurred to me is that the platform it was designed for must have been very stable in order to get the object on the bubble. It will be interesting to see what appears in the window when I figure out how to put 24 volts to it.