It is common for the DI images in the HB SI units to be "less than expected" ...
There is no "down pointing" piezo in the SI xducer ...therefore the DI image is a computer generated rendering from the data received in the "side pointing" SI piezoes ...
You can get somewhat better SI images by scanning known structure off to the side just a little ... This puts the structure closer to the "Main Axis" of one of the SI piezoes where it will reflect stronger echoes ...
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Intermittent shutting off is usually attributed to a bad connection somewhere ... The cable collector, fuse holder, battery connection, etc ...
Try wiggling the cables at the back of the head unit and see if you can force replicate the issue ...
You might also try bending the pins in the power cable end just a tad to try and create more sideward resistance of the pins in the sockets ...
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If you don't know the HB service center in your province of Canada ... You can call the main head quarters in Eufaula and they can tell you the steps you need to take to get your unit in to get the 800kHz washout issue fixed ...
1-800-633-1468
Rickie