I installed a Garmin 160 fishfinder beginning of 2000 season whch worked fine all year. Since launch this year, it intemittently flashes and doesn't come up with the ground display, I assume because of poor signal. I've fiddled with the gain without any success. Anyone any thoughts? When we launched we laid on soft mud and I wondered if any might have stuck and weakened the signal, however I would have thought it had washed off by now...