Should have been covered during class, leave it on #2.
If the knob gets knocked in either direction there'll be another sensor.
Simple math, really:
A sensor costs $75, a new secondary $450 (last I checked, anyway).
Replacing a sensor should take no more than a couple of days, probably next day in MDR.
Replacing a secondary can take weeks, if not months.
So even if there's an appreciable use of the sensor, you rather want to get a new one than a new gauge.