Elite 5 hdi problem

[YakDout]

Hey guys, wondering if anyone had ever run into this problem, or knows what this may be caused by. I have a lowrance elite 5 hdi unit that I am getting vertical lines spread through out the screen. The lines area sometimes there, and sometimes not. When they do appear, I don't lose any quality of picture on my screen, but they are an annoyance. They also clutter the screen. Adjusting the sensitivity does not help when the problem occurs. The transducer is mounted in a lowrance ready bay, however I had the same problems on my last kayak, while the ducer was on a ram ball mount. Could this have something to do with wiring? Interference from something since it comes and goes? Bad unit? I will take a screen shot of the FF next time I am out if I cannot figure out the problem by then.

Thanks