Make sure the motor is not in the "beam" of the cone. Check with the motor down and using the level mentioned above check to see if anything is in the beam when the boat is sitting in the water. You may need to move the ducer to the most right or left side of boat away from motor so the beam does not hit the motor and blade when scanning. If that old ducer is in the beam then it will show up as well. Use a string and tie it to the sonar and pull it out at an angle from the ducer to see what is "in the beam" from all angles. If the string hits anything then you need to move the obstruction or relocate the ducer.