Newbie here.. Having trouble with my TrackerIV. This the first place Ive looked. My detector is about 5 yrs old and has been working great. Until today. I noticed when I turned it on the battery light lit up so I replaced the batteries. Now, it will power up but will not pick up on anything. I have checked that the cord is all the way in and tried another fresh set of batteries with no luck. Im not sure what else to check. My thinking is the coil wire....any ideas?