65 Barracuda dim dash lights - no gas gauge either

I think the dash light bulb holders ground to the printed circuit board which in turn is grounded through the screws to the cluster housing. I have seen these screws corroded and not grounding the circuit board to the housing. This ground must be good as well as housing to car body. Then, are all the bulbs working? Yes, stock bulbs are dim, check them at night to condemn them..If you need more illumination you should consider LED replacements.