Went to an old home site with moderate to extreme trash. I have hunted this area once before. My etrac was running at 25 in auto plus 3, so I elected to run in manual 25. With my disc set at 27, after a few minutes walking around, I decided to go over the area close to a well casing where I had dug an old wheat on the prior trip. I scanned the area, had a lot of falsing and detected nothing and decided to go to auto plus 3. I got a good repetitive high tone with depth gauge half way down, turned 90 degrees and the tone was scratchy. Turned back to my original position and watched the screen 24-41, 25-41 and it continued to alternate for the most part. Went to quick mask and the ferrous numbers stayed at 24/25 and about every 6th or 7th sweep it would jump momentarily to 12/13 and go back to 24/25. Before I dug I went back to manual 25 sensivity and heard nothing but what sounded like falsing. Dug down around 7 inches and recovered what looks like a copper thimbal. It read 12-40 on top of the ground. It seems auto sensivity has its place when using this machine.