I was detecting on a farmers field last year and the ground was just right as in flat no stubble, but very dry n dusty as it had not rained for a while, Anyway i noticed I was getting a lot of false signalling more than I'd experienced before, So much so I was checking under the coil to make sure a piece of silver paper or something hadn't wedged itself to the coil somewhere. At this point of picking the detector up by the coil i noticed fine dust like sand had accumulated inside the coil cover, so i shook the detector to get as much of the dust out, but some still remained...At this point i realised the coil cover has to come off to give the coil and inside of cover a good clean....Anyway i don't know if they glue theses covers on at Fisher but it took some prising off. Now i find it dosen't fit snugly as it did and I have to use plastic insulating tape to keep it on........I think Ill refit & seal the coil cover with some aquatic silicon. .......So just a tip, if you get a lot of false signals check the coil cover to see if its holding dust fine soil/sand or even worse silver paper............