Oil lamp font help

Hello
Someone had at one time or another converted the GWTW lamp below, damaging the collar, but fortunately did not drill through the base up through the glass font. When I first looked at this font, I thought it needed a spacer between the base and the font, but upon closer inspection and disassembly the base of the font has a metal cap, it appears to be threaded. This is new to me, I have a composite lamp, but it is nothing like this. Does anyone know if this font actually screwed into some sort of base and if so what it was constructed of and looked like? I can likely make it work with a spacer, but I am wondering now if this was not married to the metal base as a work-around at some point in time. Always up for learning new things, any feedback \ direction would be greatly appreciated.

 

We need more photos.