With 5 volts going into one side of gauge do you get a voltage reading on the other side?

If not, you've got an open circuit inside the gauge. Windings in gauge may be toasted.

This happens if the voltage limiter ever failed in the closed position, which sends a full 12 volts through your gauges and fries every one of them.

Happened on my rallye gauge set. I use the RT Engineering limiter now.