I've got a MTD lawn tractor 12.5 briggs have the same problem that was posted earlier. I did jump start it and the starter works. I changed the switch and solenoid. The switch will kill the engine. When I turn it to start it will not engage the starter. If I jump across solenoid which is under the seat it will start. With a tester hooked to ground and touch a prong on the start switch I get a light when I turn the key to start the light goes out let of the switch and light comes on. This happen with the old switch and new. It was working fine then started the problem above. Any help will be appricated. Melvin

I'm sure the switch is a mtd replacement?
Go over your wiring real quick and make sure nothings rubbing, broken, bare and touching... that sort of thing.

Battery and starter cables but what other wiring goes on the solenoid on a Briggs and stratton 12.5 r4iding mower by Murray