I'd have to agree with BigPapa on looking for just replacement switch. Might even be as simple as getting a safe contact cleaner to clean contacts on the switch. Could Geno's provide the manufacture of the knob to reach out to them? Check with a heavy duty truck shop or forums to see if there's something similar out there. Good luck on the hunt.I would think you should be able to remove the knob then remove the switch. It’s probably a pretty standard switch.