67 barracuda , no power , lights nothing ?

RedFish said
Maybe. It is one of the better built amp gauges. I would look closely at terminals in bulkhead connection. Plastic connectors melt terminals push away.

Yes. Also I've had situation on connectors where the terminal backs out when the connectors are assembled. Got to make sure they are hooked in well.

Arrow points to male terminal barb that needs to be expanded before reinstalling into connector.