There are NO contacts on an HFM sensor.
The sensor has a heated ceramic plate that has a film on it that is cooled by the mass of air crossing it. The air pulls heat away from the heated film and that changes it's resistance. That is wired to an internal wheatstone bridge circuit that attemps to balance the resistance of the circuit, thus the output of the sensor changes as air mass increases.
So, NO contacts OR any moving parts ..it is simply an integrated resistor circuit that is air cooled sensed , amped , and balanced ...what you are cleaning is the surface of the Film substrate..as they get dirty, their sensitivity to the intake air crossing it deminishes and therefore gives a false reading to the bridge circuit.
Simply spray clean the unit well and ley it dry. You want any oil/dust/dirt off the sensors film plate.
That is why HFM and LH [ hot wire] do not like the oil bath filters some guy use for power/breathing enhancement.. these allow a slight oil film to accumulate on the sensor and the oil collects dust, thereby cutting the sensor sensitivity to the air mass ..always use a paper filter with these.
[ and a clean one]
The older Hot wire sensors were less susceptical to this b/c they had a pre-start heating cycle for the hot wire to keep it clean [ debrie burn off ].
The newer technology AMM work on Frequency output vs voltage output. Along with wide band 02 sensors...

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A Dalton