We have a tank indicator on our 2005 Hunter 33. We recently returned from a sail and there were only 4 blocks out of 10 present. We brought 2 gallons of diesel and added to the tank. When I rechecked the indicator it showed only 1 square. We added 2 more gallons and it then had no blocks indicating empty. We then went to the marina and filled our 25 gallon tank but the idicator still shows empty. Any ideas? The fresh and waste water indicators are still functional. I read the material with the tank indicator and it said you can not recalibrate the fuel indicator