Hi LD1,
Well, as life happens, I didn't have a chance to look at it yet but maybe tomorrow. So far I am really suspecting the "ignition switch" if we can call it that, you know, the thing you put the key in.
At the end of the day I topped the fuel off and was going to move her back to the shed, climbed back on board, pushed the clutch peddle fully to the floor and twisted the switch and nothing, absolutely nothing other than the normal dash lights lighting, no starter click, no nothing! Double checked everything else just to make sure I hadn't moved the PTO switch or something stupid like that, checked the turn signals and lights and all appeared to act normally.
After twisting that darned ignition switch about two dozen times, it nudged the starter once and then about a dozen times later she finally came back to life as if nothing was wrong.
I'll try to put an indicator of some sort on the starter solonoid tomorrow and go from there. If that shows me nothing then I'll probably add a push bottom switch on to bypass the starter (and all other safety switches) and see what happens. Understand, I'm not recommending or even suggesting that you try this but those are my own personal plans.
Will keep you posted but it may take a few days. Unfortunately that's not the highest priority on my list as I have other tractors if a serious need arises and the snow is going to be here sooner than I'll be ready for it.
Continued good luck with your fix and yes, I have the full set of "official" Kubota manuals for all of my machines but I must confess that I haven't read every page (yet).