Fuel Gauge Issue

[72 CO Blazer]

I'm very early in the process of trying to sort out an issue with my fuel reading. For years the fuel gauge was simply "dead", meaning that it never moved from reading at the Full Position. I recently pulled my instrument cluster and wound up replacing the printed circuit on the back. When I pulled the cluster out of the Blazer and there was no power, the needle remained at the Full Position. After replacing the printed circuit and reassembling everything I turned the key and the needle moved to the right - indicating that it was even more than full. Before I begin to chase down wires, the float, etc. what is the likelihood that the gauge itself has the starting point (i.e. and empty reading) wrong. I guess this same question put another way - should your fuel reading when the instrument cluster is disconnected read "Empty"? If so, can the starting point of the gauge be re calibrated or does the gauge simply need to be replaced? Thanks in advance for the help!