On the Clarke CBS45MD saw I bought years ago, the first NVR lasted about 10 cuts. The second NVR lasted a week. There was a few choice words during that saga I can tell you. I ended up making my own switch out of a contactor and a few machined parts, and no problems since.
When they first appeared on machines in the workplace and made in England or even countries like Italy they were fine. The quality of Far East switches is dire to say the least. Even the very basic forward and reverse switch on my Lathe has lasted operations only in the very very low hundreds if that.
It's never the stop switch that breaks though is it?!
That used to be the case Chris, but thanks to us having to come into line with Europe (I don't know why, UK electrical systems and equipment has always been far in advance of the crap in Europe, oh I get it, it is so they can sell their crap over here) we have changed round, and I think you will find that "UP" is the new "DOWN" As an electrical Engineer with far too many years experience, it really pi$$es me off!
Just to add, the last NVR starter I fitted was to a 5HP Ingersoll-Rand compressor, I bought it at an electrical wholesaler local to the job for about £50. It was made in India, very cramped inside, so difficult to wire, but it worked ok, and afaik is still working. I checked it up later on Alibaba, if you buy an assorted container load, they cost $4-50 each!
As an electronics design engineer of almost 40 years experience before retirement, I can assure you that for all that time, most professional quality test equipment, on both sides of the pond, uses 'down' as the off position, push-buttons excepted!
In an emergency, it it much quicker to turn equipment off by knocking the switch down, rather than up! Hence emergency stop switches use push-buttons, rather than a pull action – it is just the same! Hence I do regard the use of switches with a down 'on' position as intrinsically less safe.