Actually, it is Bakelite. It is more brittle than plastic. I got the knob off. I put a screwdriver in the slot the knob goes on to and twisted the knob back and forth and wiggled it off. It took some doing though. It was really on there. It was seized right to the shaft. I'm glad I did too. The spring I mentioned earlier fell out of a hole in the back of the knob. I also have to get to that side of the mechanism. It is really binding up. Something is wrong in there.
~G~