Rallye Dash Resto

It wouldn`t hurt to clean up each individual ground screw for terminals 1-4. It sounds like you`ve got the panel grounded well, but do you have the printed circuit grounded well would be the question? If the voltage is constant,bulbs are the same, bulb socket prongs are clean and making good contact, then I would look to the ground screws between #`s 3 and 4 and to the upper left of 2 and 1 as in your picture. If you have to ,jump a ground wire directly to the screw head (once they`re cleaned) and see if that doesn`t solve the problem. Good luck and hth!