Got a 2000 ultra with a fluctuating gage gage. Riding down the road it reads fine. When letting off the throttle to slow or to stop the needle moves back and forth about 1/4 tank. At idle it reads fine also. Unplugged wire under seat to ground it out and the gage moves rapidly from emtpy to flull. Has the dampner gone out of the gage? What's the next troubleshooting step?