Just a side note, Robscastle: Many of the switches sold have less than high quality soldering, so can fail at an easily repaired (re-soldered) joint.
I have an auto switch on my miter. It died about a year in. I was bummed and tossed it, but became curious on its guts, so I broke it loose from the back and was dismayed at the crap quality of the joints. I re-soldered several of them, plugged everything in and it has been going strong two years later.