For those interested, I've replaced the nubby knob on my original Colecovision joystick with a nice quality ball knob. Check it out.
The procedure is easy to do, and easily reversible. Here are the left over parts:
There is some great info over on Atari Age in this post. Although the group order is over, there are a few users over there that have leftovers and are selling them individually. And if there is a lot of interest over here, I'm sure we could do our own group order.