I have a new F75 that is a great detector and I am impressed with the build quality. It is the upgraded version, but after the first twenty hours I thought I felt some wobble in the battery box stand. I now have about 50 hours on it and the box is definitely getting looser. When I first felt the stand move, I found a phillips screw at the very end of the shaft with the battery door off. It was not loose, but I tightened it as much as I dared. Also, I found an allen screw at at the front, underside of the box. It was not loose either so I backed it off and retightened it. I never tighten a small screw to the point of stipping it, but I am puzzled because both of these screws were tight, but the box was loose. Since that episode, the box has loosened even more. I hate to send the detector back in the middle of the season and I was hoping to do it when winter comes. Am I missing something here and has anyone else had this problem? Thanks R.L.