That picture is good but it's not quite right for the D15Z1. The cam gear isn't meant to line up with the head surface. There are little arrows on the belt's back cover that it lines up with just counter clock wise from the head's surface. I realize that this thread is old news, but that was what i was trying to say may be the problem. That maybe his was lined up like in your pic when it should've been lined up with the arrows and could've been off by a tooth.