I red 
this thread and it looks like it would be difficult to remove the ball from the shaft without damaging it.  I wonder if the shaft itself with the ball can be purchased from somewhere.
I'm hoping to install a shaft with a larger ball top.  I've never liked how little the original one is, and would also prefer for the ball to be smooth and glossy -- come now, most of us are adults by now  

The last post mentioned tornadoterrys as a source for the shafts but they don't seem to sell just the shaft anymore.