Others here probably have more direct experience with your model, but I would suspect the needle valves and/or the float heights.
Float height is set by adjusting the bend angle of the small tab that contacts the needle valve. If the float height is bad, the fuel level cannot get high enough for the tab to close the needle valve.
If the needle valve is bad, it doesn't matter if it gets closed or not since it doesn't seat properly.
Changing the float height is free, so it's probably the needle valves (unfortunately).
Rob