I took another look at my pump and my previous comment assumed that the glass on Brian's pump was close to the dial face. Upon closer inspection it looks like the glass may be missing, as the slot around the outside of the face pan is very evident, or the glass is extremely clean and missing it's span rings.

Did some more cleaning and tinkering with my pump. It appears that there is a fitting inside the hollow knurled knob. The face of the fitting has a hole in it which I believe is threaded to fit over the rod that holds the hands in place, There is also a slot in it but the edges of the slot appear damaged and a screw diver will not bite in a counter clockwise direction. The edges of the slot are good for a clockwise direction. I would appreciate it if someone could tell me which was the fitting needs to be turned to remove it from the rod!