If it was mine, I'd fill it full and slosh it around a bit to maybe jar the mechanism loose.
"COMPLEMENTARY" How did you get that service. I think the dealers are true a-holes.redrider said:It will show empty..the reason I know is I took my bike in for the first "complementary" service and they removed the tank because they were checking valve clearance. When they got all done it had a full tank but the guage was pinned on empty because their "master technician" had forgot to hook up the wire.