The end that the knob goes on has a sort of serrated edges on it and when the knob is tapped on the end of the arm it will stay there. If for some reason it is a little loose then a dab of glue should do it.
I just did this last week. My old one was tough to get off but after I cleaned and painted the arm up I just tapped the new knob on and it stuck nicely.


1937 Chevy Pickup
In the Gallery
1952 Chevy Panel
In the Gallery
More photos
1950 Chevy Coupe
Pictures!

I'd rather walk and carry a Chevy hub cap than ride in a Ferd.
I can explain it to you, but I can't understand it for you smile