I have a Garmin 250 fishfinder. Occasionally the depth display will blink and go blank. It may come back in a few minutes or if powered down and up. It may happen at slow or fast speeds. It may happen while drifting and fishing. Garmin said it is cavitation. But it happens even while drifting. I have increased and decreased gain with same results. I am not sure if it is heat related or not. I have checked all electrical connections. I have repositioned and leveled the transom transducer with no results. When the depth is lost the scroll continues. Sometime it may go three hours without losing the depth display. When it starts it does it often. Any ideas? 
