Yesterday I pulled off the seat back to do some investigating. I gently removed the sending unit and measured about 1/2 tank. When I looked at the gauge , it showed about the same, a little less than 1/2. When I switched on the key the needle slightly moved to the right. Next, I'm going to fill the tank an see if the needle moves any further. I have never had a full tank or really looked that closely at the gauge needle. The case continues....