Are you leaving the gauge in place in the dash? I had one in a 1950 that when the needle moved in the dash it would move so far then get stuck on the back side of the divider that has the lettering on it.
Once I spaced it away just a little the needle moved freely from F - E
If you are leaving the gauge in place while testing then this isn't the issue if ti will go to F - E while moving the arm.
The float might be hitting the side of the tank as it raises. It may be clocked right for the mounting screws, but may have to tweak it just a little to keep the float from hitting the side.
