fish finder

[Adayonthewater]

I have a question? About two years ago I got a Hummunbird 757 w/dual beam transducer. I mounted it on the transom of my pontoon fihing boat and could not get the wide beam screen to show. Sent transducer back. Humminbird sent me new one. Transducer now shows wide beam and both split screen images. Problem is I can't get it to show fish. I see fish on it sometimes, but other times we will be catching fish near the boat and won't see them on the screen at all. It also advertises that you can see groups of baitfish and even see your jig. This has never happened. I am now wondering if I should just get another fihfinder, maybe Lowrance and dump this one, or try to stay with this one. I have spent days adjusting every thing I can think of and trying all sorts of combinations, just am not happy with results. Suggestions?
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