I have a Garrett AT Pro and I'm having an issue with it. I have returned it to Garrett numerous times for repair to no avail. They even sent me a new AT Pro but the issue persists. The issue is that when detecting in a field if there is a tiny, single, taller spring sticking up higher than the grass and I hit it with the coil, I get a coin signal. However, there is nothing there. It makes it very difficult to hunt. On the beach it does the same thing if I accidentally touch a mound of sand. Has anyone else had this issue? Any ideas on what may be causing this or how to remedy the issue? Thanks for any suggestions.