My mini's push button is quite difficult to depress. As a result I stick with my grand. When I look at the part of the push assembly that touches the battery, it is different between my grand and the mini. The grand's tip that touches the battery is fairly flat; the mini has a pointed tip with which it pushes the battery. Not sure if this is normal, as designed, or whether this twisted "tip" is causing the difficulty in depressing the mini's push button. Any ideas?