Fuel gauge stopped working

[data89]

1969 C10 Stepside, 7 gauge panel. All of a sudden my fuel gauge stopped working in 18 years without having done any work on it. Stuck at 3 o-clock.

Have made the usual checks...grounded tank wire with ign on and gauge needle went ccw down like it should. So gauge is working, right. With tank wire on and ign on I get 8.4 volts at the tank and 8.4 volts at the spade connector in the fuse box, so no short in the wire. And, the connection to the dash panel must be good to get the voltage at the spade connector. Am I looking at a bad sensing unit in the gas tank? Is there a trick getting that out?