I just installed an Eagle Pro ID 128 on the bow of my Nitro,and I'm getting a little interference when I first click the trolling motor on. I wired it to the power wire for the navigation light up front, and the transducer is on the trolling motor. When I first engage the motor, I get a line on the screen about a half inch wide, that disapears as the chart advances. It still works, so I don't know if this is common or not? Any advice appreciated.