incorrect fuel gauge reading

Got a 2002 Beetle with it's fuel gauge reading incorrect. When I fill up the tank it shows 3/4's on the gauge. In your expert opinion, the sending unit or the gauge? Seems like its getting worse with time which leads me to think, sending unit-float device. Maybe you've seen this. Thanks........

I would tend to agree with the first assumption, the sending unit and/or float. But VW's are known for terrible grounds and wire corrosion. Added resistance from not having a full ground could lead to a bad reading. I'd follow the ground wires first since it is easier than opening the tank.