my unit started acting up this past weekend. been working perfect until now. I launched the boat this past Saturday. when I turned my 598 on it displayed I was in 1500feet of water. I was in only five foot. the di and si images was black with no image. the 2d sonar was a normal screen showing the bottom around a foot deep on the scale but still showing 1500 feet deep. water tem was accurate. I put the depth finder in simulation mode and everything worked fine. I think the transducer clunked out. any suggestions?