sorry to hear so many troubles. They seem fine on my own Metallica but I realize conditions can be different for everyone. Clean well around the mag poles to remove any wax and dirt, peel backing and stick down and rub down hard with a polishing cloth. The 3M adhesive is pressure activated and achieves full cure in 24 hours. Another suggested tip is to adjust the magnet pole upwards just slightly to match the height of the ring, only about .005" or the thickness of a couple pieces of paper. This should prevent the ball impacting the inner edges of the ring.

The single drop target protector is a clip on style like the majority of my protectors. It uses no adhesive.