Those were not my words... that is why I quote what others say and provide the link to said quote as I am providing info I am not certain about, just offering info. As "Dave" mentions if it lowers resistance, then any voltage on the probe will send a milli/microamp flow thru the circuit or as you mention a thermocouple will produce a voltage, I dunno which. Please provide a link to how
it actually works, cuz I cannot find info on this old style, I was very happy to find
Daves Place, a trove of old equipment info, a permanent link for sure.
Now OP, as mentioned try contacting Dinosaur... I am out of ideas.