not sure on how old your unit is but on some of the older lowrance lms series if you didnt have the waas enabled it would not find your present location very well and would cut in and out,as well cause its an internal antenae make sure the unit is as verticle as possible not leaned bak on a slant as most of the antenae is on the top,my lowrance was like that too,and that was about 5 years ago ??/ just shootin out ideas for you too try ??/