Could use some help on my 597ci di. The unit is about 5 years old. I used it for a week back in June on a Minnesota fishing trip, worked fine. A week after returning, trying to use the unit and it no longer shows bottom or structure info accurately. In water I know is 15 feet, it reads 700+ feet of depth. GPS works fine. I've cleaned off transducer; checked connections, but all to no avail. Any suggestions on next steps? Is it likely transducer related? Time for a call to Humminbird? Appreciate input. Thanks in advance.