We bought a couple of tools at a school auction recently and all of
the 110 V tools there had a little yellow box called a Saf-Start on
the cords.
They seem to be a device to prevent re-start after a power failure or
a low voltage situation. Once you lose power you have to re-set the
button on the yellow box before the machine will run.
I checked the website http://www.jdsproducts.com/products.cfm
and it seems they have replacement pigtails or one model with a plug
so that you can add it to the existing power cord instead of having to
wire into the switch. There is also a 220v 3 wire model available.
At $90 it seems a little high but it may be cheaper than a new
magnetic switch.
I guess the school liked them because they had them on everything.

Mike O.