Ok, you folks rock!
I lifted the rig and tested each wheel by spinning then pulling the emergency cord. Driver side checked out fine. The passenger side however didn't fair so well. In fact, neither of the two wheels showed any braking capacity at all. Upon inspection, the front axle had a frayed wire at the connection just outside the drum! Whew - easy fix! The rear axle wires were good on the passenger side, but when traced back to the driver side, the sending wires (that run through the axle from left to right) were frayed. Whew - easy fix #2. Perform spin test again - everything works. I then connected the truck and took a few victory laps around town.
Thanks so much for the help!