Heil furnace leaks gas
My Heil combo force air a/c-furnace unit started to leak gas. Gas company determined it was the 24volt gas valve inside the furnace leaking. Tech thinks it's the gasket inside the valve unit that went bad. The furnace heat function operates correctly, i.e. turns on and off as needed. Suffice it to say, I shut the gas line off.
The official part name/number is: Valve, gas(nat) #612916.
It looks like it's pretty straightforward to fix (although I've never done any gas work other than capping off a no longer used line). The replacement part is a complete unit that has 3 hookups into it.
Is there any chance that a different part in the furnace is faulty and is telling the furnace to keep the valve open ever so slightly? The leak is very slight...no hiss but noticeable smell near the furnace.
I have a voltmeter and some/little experience using it. Is there anything else I should check before ordering the replacement part?
The part is $250 and I want to make sure identify the faulty part correctly.