Put one of those $10 machine levels from lowes on it and check for plumb and level install. Just because ranger put it on doesn't mean it couldn't have been done on a Friday! And don't forget, level on a slab under ya boat shed is not the same as level on the lake cruising at sidescan speed.

Also get down level with it, looking from the starboard corner of the transom looking towards port side. If anything is in the way you'll see it.

All of your settings are correct, e.g. frequency, range, etc.?

In no way do I intend on insulting your intelligence; just brainstorming ideas on what must be a frustrating problem. If you're running the wrong frequency at the wrong time, or running 150 foot range in 8 FOW then you're going to get poor results.

If none of that solves it, then I pray you got backup from ranger, because God help anybody who has to turn to Lowrance's customer service.