I sent unit in for diagnostic and they sent the unit back and it worked fine when I got it back, until I did the new 7.080 download. Then the depth readings went eratic again. The techs told me to load the newest download of 7.090 and retry the unit again? Why do you think they came out with two new downloads in one week (7.080 and then 7.090), do you think the first one was a bust and that they had to correct the problem?