I just bought my first detector and I'm having troubles that I don't know if the cause of is me or the detector. I bought this unit used so I don't know if there's anything you need to worry about but. I was at the UofA campus searching in the sand and I would toss a coin down in front of me and still not really find any signal. I found a pen, a fitting and a penny with the machine as well as a nail so it works but... I went to a school yard and couldn't move 4 inches without the thing beeping at some piece of foil so I couldn't figure out what to dig up... Should I just hunt in all metal mode for a while? If I hunt in coin mode will it pass rings over? I put out a gold ring to see if it would find it and I just passed it over in coin mode. So let me know, any help would be great!