I have a hum- bird 597hdci or ci hd whatever. It has the down scan. It is two years old and has probably been used a total of 40 hrs at most. The last trip out with it the depth reading went crazy. Would jump from the correct depth to something like 40-60 or 90 something feet. It was not staying at the incorrect depth just jumping there for a second and then right back to the correct reading. Just jumping around crazy. I was in basically 10-15 ft of water. The graph still displayed the correct reading and showed bottom just fine. Its just the depth reading in the upper left corner that went goofy. I checked my transducer and it is still in same position it has been since mounting it. Not motor interference cause I shut motor off to see if it was that. I shut down finder. unplugged it a couple different times. Didn't seem to help. Any suggestions. (other than getting the other brand). That will be my next investment.