Internal light switch knob failures

Last night, my headlights would not switch off. I was hoping that it would be the common solder failure of the wire, but unfortunately the failure was inside the top of the knob itself. The little cam/notch which opens the contacts inside the switch failed. (See picture). I guess after forty years anything can be expected. Unfortunately, I can’t find any replacement knobs. Does anyone have any ideas? Even a replica or 3D printed knob would be better than nothing. Hopefully someone knows of source for a replacement.

Thank you all,

Jan
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Awesome. Thank you!