1938 P-6 Headlight Knob

[Lindsay McConnell]

I am not sure how 38 headlight knobs originally attached. My question to you is once it is attached, is the knob removable?
1939 and up H/L knobs use a small folded metal clip, with a receiving hole in it to grab the shaft when pushed on. There is a small slit in the knob where you would need to insert a very small blade screwdriver to compress and release the tension on the clip to safely remove the knob.
Maybe someone can shed light on the mystery of the 38.

[atlbluz]

I found an original knob on e-bay.  It will not stay on the shaft when I pull it out to turn on the lights.  Anyone have an idea as to how to get the internal teeth to bite on the shaft?