A long troubleshooting process
I have a MacBook Pro 13 inch that started to have a serious performance problem. Like all troubleshooting processes start with memory. So I increase to 8GB from 4. That didn't seem to be the problem. Next upgraded the hard drive to an SSD that didn't work there was something I was missing so I tried different hard drives and noticed that I couldn't get the drives to install OSX. Verified the drives that were working by installing them direct through USB put them into the MBP and nothing was happen still. That left the ribbon cable or controller. Of course if the controller was having problems then the existing hard drive wouldn't even work but it did a bit slow. Purchased the hard drive cable plugged it in and voila super fast SSD speed hard drive. The complete troubleshooting process took me like a couple of weeks.
Simply follow the instructions on iFix and with very little to no pain, the pain being having to deal with those small screws. The installation went with out any problems.
Invest in a better tool kit. That's why I bought also the Pro Tech Toolkit. By the way an excellent tool kit to have around. I was using a bunch of different tools not necessary design for replacing a MacBook Pro.