Fuel Gauge issues

I'm just about finished on my 75 project car.  I recently started having issues with the fuel gauge.  The needle stays on Full regardless of how much gas is in the tank.  I recently painted the car and I thought when I replaced the rear lamps I might have pulled a wire going to the tank.  I checked underneath the gas tank and traced the wire to the tank.  I can see a wire going to the side of the tank on the drivers side.  It appears to be connected to the tank.  I can't find any unplugged wires.    Does anyone have any ideas?  Thanks!

Could be the sending unit or a pinched wire. I think if the wire is pinched and going to ground it will make the guage read full. I'm sure some of the electrical gurus here will identify the problem.
Scott

Thanks Scott.  I'm hoping its just a pinched wire.   I have never replaced a sending unit.   I'll re-seat all the lamps.