Some links for anybody who comes looking for this info later.
I think this is the original print head and does not apply to the aerostruder.
Some discussion you might find useful
Still haven’t solved my own problem, need to disassemble it and figure out why there’s no closed circuit from the nozzle to the sense wire. Pondering doing the nozzle swap to see if that fixes it, but I’m thinking not because the heatblock does not have continuity either. Maybe the heatbrake and block are not in good contact.