Hello everyone. I have a '69 Impala Custom Coupe that I recently purchased. The current reading on the gauge is a few marks above "Empty". When the car is idling it fluctuates up and down a few bars. Furthermore, when I turn on the headlights, the gauge drops far below the "Empty" mark. I have cleaned the ground wire with a wire brush and reattached it but that did not solve the problem. Can anyone explain how I can repair this?