Thanks you for this excellent guide! This was the first time I did anything more involved than changing RAM so the guide was really helpful. As for many others, the problem was that I got the dreaded "question mark in a folder" image upon start up, indicating that the OS could not be found. I managed to make one recovery start-up to repair the hard drive but the problem persisted, I then found comments about the hard drive cable often being the cause of this problem and this article allowed me to buy a new one and install it. Easy and quick!

The cable I bought fit perfectly and had the IR sensor included. It is a MyArmor Replacement 923-0104 HDD Hard Drive Cable 821-2049-A With Bracket for MacBook Pro 13" A1278, £16 on amazon.co.uk

Also bought ACENIX® 3 Pcs Nylon Plastic Spudger for £4.