So, have a MacBook unknown late 2008, cracked the trackpad from "excessive use" dragging and dropping/copy/pasting stuff....replaced under AppleCare, no issues....gave it to my wife once repaired......bought a new 15" i7, cracked the trackpad same manner....barely putting pressure....clean breaks....getting replaced under warranty now, but frustrating....typically use mouse and more conscious about pressure but still cracking...what are the do's and do nots?