Oven probe thermistor inoperative
It turns out that the probe works after all; I'm not sure what was wrong. I did have to twist the connector back and forth a few times to get a good connection and reading. Anyway, in the meantime I did the science experiment of measuring the resistance vs temperature for this probe.

Here's the data:
T:  41.4, 80.9,  108.5, 118.0, 135.0, 142.4, 148.7, 156.7, 166.0, 176.0    °F
R: 158.9, 44.64, 22.78, 16.31, 13.20, 10.07,  8.37,  7.00, 5.673, 4.827  kOhm