The ground wire is intact but suspect, it is original from the sending unit screw to the cab, I'll replace that. The gauge bounces rapidly, not a slow rhythmic oscillation as one would expect. Thank you for your input as I have no prior experience with this vintage to judge it. I replaced the entire wire from the sender to the gauge and the post on the gauge is clean brass, I'll run a new ground wire to the battery and see if it improves.


1957 Chevrolet 5700 LCF 283 SM420 2 speed rear, 1955 IH 300U T/A, 1978 Corvette 350 auto, 1978 Yamaha DT175, 1999 Harley Davidson Softail Fat Boy