I was starting to have the 'spinning beach ball' and hard drive issues, until it just would not work. At that time, I had problems with my back up drives and had no back up of my data. I thought that the drive was dead and that my 'life' on the HD was gone. What a sick feeling. Apple Store recommended contacting these services to retrieve data off my drive. They cost $$$. As it turned out, a friend put the drive into an external USB case and it worked! I put a new 1Tb drive in the MacBook Pro and it was not recognized and I could not initialize it. I then realized it was the HD cable. Until it came in the mail, I booted off the USB drive.
Super easy. I did not disconnect the battery since I did not have a star screw driver. Everything is wonderful. Now I have a one terabyte drive, my data is backed up, and life is good.
Hint, pay the less than $2 difference for Priority Mail. It went from the West Coast to Florida in 2 days.