Fuel gauge Intermittently worked,..now nothing. 66 Valiant

My fuel gauge Intermittently worked in my 66 Valiant. Now it seemed to stop for good. All my other gauges work. I grounded the sender wire and the fuel gauge doesn't move. With that said, is the instrument cluster hard to take out? If so does anyone know how it's done? I see four screws that holds it to the dash, but after that,.not sure what else needs to be removed so I can test the sender wire for continuity or see if anything is disconnected or broke. Does the sender wire go directly to the gauge?
Thank you....