You can check with an ohm meter to see if basic functionality is working. Nothing on seat, should be open and infinite resistance. Switch closed, and you should read close to 0. Now this doesn’t tell you if you have a voltage drop across the switch. Not sure how many safety switches you have on your machine. Best to download a WSM and look at the circuit. The end of this circuit should connect to the starter solenoid and provide the 12V needed to let the starter engage. You can check that by setting your meter to volts DC and with the positive lead to that wire at the starter and the other lead grounded to the body, you should see 12V when you attempt to start. For testing purposes you can jump across the connector that plugs in to your seat switch which will take that switch out of the circuit. Reconnect switch when done testing.