Grounding the instrument voltage regulator

Its fairly easy to tell what slot is what when looking at the circuit board.
If you're looking at only the limiter, ground comes off the top or back of the can.
12 volts is horizontal spade in the center. Pulse voltage out is vertical spade at opposite end from ground.
Testing the mechanical limiter and proving it is good is nearly impossible. It puts out a pulse voltage that makes most digital volt meters act crazy. A good analog meter will display better.