Humminbird helix 10 chirp sonar and Di mounted on bow of boat on a Terrova trolling motor. Everytime I use the trolling motor I get slight interference and depth goes to max. Iv tried grounding trolling motor batteries to starting battery, iv tried grounding the trolling motor skeg to the power ground for the trolling motor, disconnected everything from battery except unit, put rubber between transducer and trolling motor, and changed fuse inside of Terrova head and still nothing worked, still get some interference and crazy depth readings. I’m past my witts end I got nothin left hoping someone’s got the magic trick. Also I get the crazy depth reading even when my transducer isn’t plugged in if that means anything to someone. Help.....