Need some help. Got it as a present. 1st one was dead on shot but broke in a few months. Benjamin replaced it with another. The 2nd had bad vibrations and replaced it with a 3rd. The problem is that I can't get this thing to scope in. Will shoot a bullseye, then next few shots, they are all over the place. Any advice on how to get this thing to be scoped in? I like the design, but I can't get this dialed in. Plus, every time I shoot, the scope goes out of focus. Any advice would be GREATLY appreciated!