There are two of these, on the rear right and left of the motor.
The picture is of one that has been spliced. The actual connection folds apart. Find each one of these, disconnect them and crank the motor. While running reconnect till the horn comes on, that will be the bad sensor.
http://www.wellcraftv20.com/communit...ing+to+repairs
If I'm not mistaken, it will start the horn without the engine on, just the key switch turned on.