Problems with the electric gas gauge system

Still having the fuel system blues – not from heat, but the gas gauging system. The tank has been repaired and refurbished; the sending unit has been rebuilt and verified with my ohmmeter before installation. It needle on the dash still doesn’t work: needle movement stays at zero, even with 8 gallons of fresh fuel in the tank. The only major part left in the system is the dash unit. PASB 1971-6 and 2006-6 were helpful to understand the system, but didn’t have enough magic for me to solve the problem alone.

The face the dash unit is excellent, but apparently the internals are not happy. I don’t really want to go back to my motorcycle days of just having to trust my math and the odometer. Can anybody recommend a reputable, reliable and good source to get these early electric type gauges rebuilt?  Herb Tull