Check if you;re getting power to the ignition switch red or red/black wire. If not,slide the left control on/off emergency cut off switch back and forth several times.Electrical spray can help too if the brass plates inside are corroded. Check the wiring for shorts and also the two connectors on the switch to make sure they're making good contact.Clean and use some electrical grease. This model had the push up start button combined with the on/off switch and a some had problems as they got older. Pushing up sends power to the small wire on the starter solenoid. Problem could be there also.

 

 

Cleaning may help as dirt is an enemy to these switches as well as dirt on the connector pins. I'd try that first along with checking the wiring before I bought a new switch.