I did hesitate quite longtime before I decide to give this a try because I am a complete novice and never opened a computer not even to remove dust. I finally decided because little by little I have lost too much of my screen. Well, I was afraid I wouldn’t understand some passages and I’d make some bad mistake. But the guide is so perfectly detailed, little step by little step, that it was finally even fun to do it. I was able to have my mac on the run again in about 35 minutes. So cool. Thanks a lot guys!