Hoping someone can help... I'm having a hell of a time with my lowrance unit. Bought it last year and it worked fine. This year is having problems reading depths, seems like any muddy bottom screws the sonar up and all i get is flashing on the depth. Any ideas what could be causing this? I thought maybe I was getting interference by another component, i added a radio to the boat and there is a speaker near the front that is close to the unit. However I put a switch on the radio so there should be no noise interference when the switch is turned off. any ideas??