2004 Fuel Gauge Variation

Hi All,

I changed fuel filter and now I have an issue with the fuel gauge. Usually I get 500 odd kms to a tank with ~7L left when I refuel. After the change on my odo it said I did 500km but the Gauge said I was just under half fuel. Refilling confirmed this wasn't the case but I was close to empty.

Now I've moved the float while car has bern runningby raise and lowering the pump which will get the full range of movements on the Gauge (from Empty to Full) which seems to work. Can anyone advise why when it is fully submerged in the tank it doesn't reflect this full movement?

Maybe it's time to take it out and see if anything's stuck?