On the older L series Kubotas, the Clutch Safety Switch is notorious for being the primary culprit in a no-start condition. It's usually a small, button-style switch located right above the clutch pedal pivot point. Because it's exposed to dirt, rust, and heel abrasion, the connector often gets loose or corroded.
just one tip from me, before testing continuity, try spraying the switch and connector with electrical contact cleaner and jiggling the wires. Sometimes that's all it takes to restore connection