Good call on the mechanical switches that use the small chrome toggles. I use to rant about them and how unreliable they could be but it mostly fell on deaf ears. So, I mostly stay silent about them these days. Vibration can easily cause the point contacts to make / break which can cause all sorts of problems with the radio. If that problem doesn't get you, the wires breaking and falling off will. Many of these switch types have since fixed their wiring problems with shrink sleeve and mechanical supports for the wires but the unreliable switches themselves remain. I don't know of any switches of that type that use knife contacts, they're all point contacts that rely on spring pressure for contact integrity.