Another picture maybe better. Once again not Kubota but to give
View attachment 51889
you an idea of what is inside.
Solved = at least in my case.
After viewing this diagram I noticed the shifter is sitting in the top fork with a little ball apparently doing all the work of moving everything inside on the top end.
I also remembered the shifter feeling like something 'popped' when I could no longer get it out of reverse.
So - my solution
that worked was to pull UP on the shifter and simultaneously move the shifter to different positions, then letting it go back down to see if I could get it back to where I felt it pop.
Sure enough, after about 5 tries I found a spot that letting it down I could feel it pop back in and whadda ya know?! ... I could shift through all the gears again.
I hope this info helps someone else who find themselves not able to shift after feeling a pop on the shifter. Give it a shot, it was 100% free.