I have a Huminbird fishfinder 525 and the depth keeps reading 700-800 feet. I have readjusted the angle numerous times and get very little change. I have reset to factor settings and the test mode indicagtes it passed all the test. any suggestions on how to repair or determine if it is the unit or the transducer?

Boating - Humminbird - Fishfinder 525 406260 1