I took this forum's advice and replaced the ignition switch after getting stuck twice for 10 minutes waiting for the PassLock to reset. Many thanks to Swartlkk and WolfPack for the great instructions. I'd like to dissect the old parts to find the failure and welcome any advice where or how to look.
The service manual has several schematic representations of the ignition switch and its connections to the Body Control Module (BCM) that are alike. Strangely, one version of the schematic shows an electronic filter (few resistors and capacitors) "within the harness" that is not in the other versions.
My experience in radio makes me very suspicious of this filter. They're often 'couplets' made of ceramic potted film resistors and capacitors; very prone to open circuits with age. After getting the harness out, I see no filter in the harness. Perhaps it's inside the switch assembly? Although the harness slides a lot with wheel tilt, there's no visible abrasion.
Any suggestions beyond a continuity check of the connecting ends before tearing the switch apart?

 

I will be doing very much the same thing with a "good" ignition switch I received from a member. Just going through it and documenting how it works (if I can).