There are (most likely) four wires going to the switch plate from the generator: a ground, a stop/prime wire (which the switch connects to ground when in the stop position), a start wire (which is likewise connected to the ground when in start), and a positive line for the light and hourmeter.
The ground would be connected to the middle of the three terminals for the switch, assuming it's a reasonably standard switch design, and also to the hourmeter and light (which is often two separate terminals on the switch body since the light is often in the switch). The start and stop wires would be on either side of the ground connection.
Perhaps the simplest way to see which is which is to unplug one of the two wires on either side of the middle ground connection and see if the stop switch ceases to prime or stop the generator. If it doesn't work anymore, that's the stop wire you just pulled. If it still primes and stops, it's the start wire you pulled. Checking that the light and hourmeter still function with the generator running would absolutely confirm this.
Edit: Too late posting, but perhaps the ideas on troubleshooting will help someone else. Good that it's all working properly now.
