Craftsman lawn tractor intermittent starting issues

For several years I've had starting issues with an, otherwise excellent, Craftsman lawn tractor 917.203810. So far I've always, eventually, been able to start the tractor. Sometimes it will start on the first ignition try. Sometimes it takes many tries. The starting sequence is proper, with the brake-pedal depressed and the attachment-clutch-lever unengaged. I discovered that shifting the attachment-clutch-lever back and forth with the engine "off" will aid starting. I suspect an electrical defect in the on/off contact of the attachment-clutch-lever, which by design keeps the the engine from starting in the engaged position, but is intermittently defective by sometimes keeping the engine "off" in the unengaged position. Does engaging/disengaging the lever mechanically activate this circuit? I don't have the technical smarts to figure this out and hope there is a simple fix. Help!