Nothing wrong with those finders. Go to YouTube and serch for fish finder operating videos. Several on there on how to use older finders. I found on using one on the front it will pick up some interference some times. It shows up as fish. When in doubt look at rear unit as you move along. Should see basically the same thing. Both of those are pretty good units. Main thing is learning how to find structure or cover on the bottom and learning how to interpret that.