I went to a town park today that had a car cruise yesterday, I did not get there till 11:30 and it was hot for me , lots of big old oaks makes most of the area shade, After swinging for awhile and not picking up any good signals ( I was thinking fresh drops) . So I check my machine by throwing a silver dime down and a Nickel, hit the dime like normal but would not pick up the nickel, I was trying all kinds of settings and nothing -O disc - -----0--90 thres---O--60 sens ----all the tones ------0--30 notch------ and all I would get is a faint grunt and not all the time. I had the Sharpshooter coil on, and yesterday at a new permission, same coil dug a wheat about 4'' down , dirt is so dry its like powder. Back to my F70 not hitting a nickel, standing there swinging and thinking this is crazy and what could cause this not to pick up a nickel on the surface. I turned off the machine and did the factory presets and everything was find. That was the first time any thing like that has happen ----Any ideas what could cause this??? ---- I found 1 penny on the street getting out of my car and not even a pull tab in the park in the 1hr that I was there. ------------after1--------