The knob screws on, but there is thread lock on them. When they're installed, they're torqued down really tight too, so the lettering lines up straight. If you know you don't want the OEM knob, get some big ol' vise grips on that sucker and give it a twist. Cutting into the knob won't work because the knob isn't threaded, but the insert INSIDE the knob is. I forget if it's steel or hard plastic.
The threads on the shaft are M10 x 1.25 for anyone that's curious.
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