For 71 the FSM says to replace the valve. 73 and later have an external plunger nub you can reset it with.

I would take it apart, clean it recenter it and reseal it.

I suppose you could pull the switch and try to recenter the shuttle thru that port.

They say there are no such thing as a stupid question.
They say there is always the exception that proves the rule.
Don't be the exception.