My HDD cable stopped functioning a little while ago, and I used iFixit to diagnose, purchase a replacement and replace the cable. Since I've been meaning to replace my HDD with a SSD to breathe new life into my slow MacbookPro Early 2011, I ordered an SSD (for the boot drive) but decided to keep the HDD (used Disk Utility to verify the health of the HDD) as a second drive. Additionally, I don't remember the last time I used the optical drive on my laptop, so when I found I could swap it out, I decided to try some DIY.
Bought the upgrade kit from iFixit, since I also wanted a minimal good set of precision screwdrivers. Opened up the laptop and followed the step-by-step instructions on the iFixit guide. It took me about an hour since I also cleaned the interior as I worked. It went well, and I now have a responsive and roomy laptop.
Use a system for screw management since there are quite a few; all of which are slightly different. Take your time with the more involved steps making sure all cables are disconnected and out of the way before you remove the components from the body. If, like me you are trying to catch an old laptop up with the times, I also recommend upgrading your RAM (which I did).