Thor, or should that be Zeus?

[AndrewMawson]

Well designed switch elements in micro-switches (or thumping big panel switches for that matter) are designed to 'wipe' so that as the contacts open they also slide a tiny bit in what is effectively a cleaning action.

A higher whetting voltage on contacts will overcome small amounts of oxidation but 'normally open' contacts that have been in previous heavy use, but are then left un-operated, will build up a troublesome oxide layer.

My Traub TNC350G CNC 5 axis lathe had sat unused for several years before it fell into my arms (not literally - it weighs 4.5 tonnes!) and I had no end of trouble with oxidised contacts - got there in the end and it's now back in industry making widgets, but those contact problems took up quite a lot of time eliminating.