Preamble note: With the cover removed the hum is definitely coming from the motor.
OK, I finally got around to trying your suggestion about removing the drive belt. I just did that and found some interesting things. First off, with the belt off the motor spun up just fine. Ok then, I'm thinking that when I go to rotate the transmission pulley it ain't gonna budge. Well, I was wrong. The transmission pulley was rotating just fine (manually). My next step in the troubleshooting process was to put the belt back on and see if things still stand where they did before I removed the belt. Belt on, wash cycle activated, and it's working like a champ. Time to wash some clothes while it's happy.
My first guess is the motor brushes are worn, but I'm open to suggestions.
I forgot to add the motor hums for about 5 seconds and stops. Seems like a safety shut-off feature.