I was able to successfully replace the assembly cable today. It was not a difficult job - just a few tight locations that would have been better served with a stubby wrench versus the full sized wrenches that I have. Nonetheless, I was able to get the job done with little interruption. The hardest part was removing the interior trim and the right rear tire.
After removing the trim and tire, it was easy to remove the access panel and gain access to both ends of the cable. Before I installed the new cable, I laid the new one along side the old one to compare and contrast them. The old one was definitely broken at the lower end where it connects to the valve lever.
I use the float position all the time during the winter for snow plowing and will try to remember to be a bit more gentle when engaging the float position in the future.
One other note - when researching the part, it appears that Kubota issued an engineering change at some point - I just hope the new ones are stronger than the ones that were used during the factory install. Also, this part and assembly is not included in the factory service manual.
Hope this post is helpful when someone else has the same situation.