I used a multi meter set to resistance.
Put the pos on the nub, then the ground anywhere else on the unit.
Then I tilted it to swing the arm.
I believe it should be around 10 ohms full and around 73 empty. I could have that backwards, but that will tell you if it will work.

Of course there are other things that could prevent it from working. The instrument vr, the gauge, wiring to the unit, and ground not being there.