Oh, man, do I ever feel foolish, but I have learned something: Never trust a visual inspection to determine that a fuse is good.
The first thing I had checked when the mower stopped was the fuses. They both looked good. After having done the jumper wire test I put a multimeter on the fuse for the ignition circuit. No current was getting through it. It still looks good, but I replaced the fuse and the mower now runs.
So, a visual inspection may tell you that a fuse is blown, but don't trust it to determine that a fuse is good.
I sincerely thank everyone who offered up comments and suggestions, and especially Restrorob.
A new problem has surfaced, but hopefully I can sort it out myself. Again, thank you.