With smaller Kubotas (and Deeres) there is often just not quite enough voltage getting thru all the safety switches, etc. to trigger the solenoid. Of course clean and sand every battery cable & start related cable end that you can find. Then suggest you try hooking a battery charger to the battery terminals on the battery. Not because of battery issues but because of voltage drops between the battery and the solenoid. A charger will apply about 13.8 volts while the battery by itself will only supply 12v at best. If it starts this way you know what the issue is. I'm not saying that's the problem, just that you should try that before doing other things.
So, of course, 1st thing that came to mind was battery.....it metered out @ 12.5 volts but we didn't have a load tester.
So we threw a fully charged jump box on it and no joy....
Went to fuses next and checked the only safety switch I know of under the seat...switch under the seat was still rigged in the "run" position, ALL fuses were intact....
Had to buy a new battery for something else, so we threw that battery in to test.....nothing, not even a click which would be indicative of a low battery....
It was then we jumped the starter with the original battery re-installed and she fired instantly. (Could have done that 1st to verify if we had enough juice...oh well)
I inspected the clutch linkage/pedal and no wiring or switch is jumping out @ me.
Hate shotgun trouble shooting.....leaning toward a relay I can't find, or an ignition switch.
Something between the ignition switch and the starter is T/U...
I'll call Messick's tomorrow......they've always been awesome. Years ago, I had an intermittent glow plug light on the dash when running on my last Kubota....they narrowed it down to 2 parts....I bought them both....don't know which one fixed it, but it was fixed....probably $100's cheaper than letting the local dealer mess with it.