welcome to the x!
if someone has been in the electrical box, and its a mess, the best thing to do is to go thru the box one wire at a time, pull each connector apart clean it witha wire brush or some emory cloth and squirt some dielectric grease in the connectore then snap back togther. you can take your start stop switch apart and clean it up and it should last you a while. done be afraid of the dielectric grease in there as well.
if you decide you want a good used start stop switch i have them in nice shape for 40.00 shipped for the blaster length wires.