A fix to J2J3J4's Bubble Shift Knob

Increased hole size to fit over shifter shaft. Mating surface added inside the hole to interface with D-cut shaft to prevent spinning.

I didn't have a screw driver long enough to attempt to use the same fastener that's on the shifter already, but it is a good enough friction fit where the concern for the knob coming off is minimal.

Slight sanding needed to allow for a good fit between the two parts.