[Dubis7]

Okay, well this turned into more of a project than I had anticipated.

My immediate reaction was to use a dremel tool and sand away a bit of the inside of the shaft. Worked for a bit, but it ended up being too loose, and the knob would slip instead of turning the set on and off.

I had to step back a bit, and looked over my parts chassis. It turns out that the shaft on my set is a replacement that's slightly too big. That explains the old knob splitting so badly, and why the new knob wouldn't fit. Now that my knob was slightly too wide to work, though, I decided to go ahead and use some heat shrink tubing on the control shaft to give it a little more diameter. Sure enough, it fits snugly and works perfectly now.

The design of the old shaft has a bit of a bump on it, sort of a spring I guess, that will actually still work with the wider knob. I may replace the replacement on mine someday, though the work I did should prevent any splitting going forward.

Thanks for all the advice, folks.