A standard AMM uses a thermistor plus a hot-wire. The platinum wire that does the "burn-off" when the ignition is shut off is a heating element.
Basically, it has 2 wires - one hot wire and one thermistor. The hot-wire transfers more heat to the thermistor when there is less airflow and less when there is more airflow.
The trim pot on old LH2.2 (or 2.0?) AMMs was used with the O2 sensor output to tune mixture. I don't believe there are ANY adjustable components inside the AMMs, but you could have the thing repaired for probably a few hundred dollars by an electronics shop like Direct Repair Labs in Beaverton, OR.
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