5 - 15 dakika
S.MA.R.T read error would not let me upgrade to OS X Yosemite.
Repair was straight forward. I nearly ruined the Monitor Connection when I first removed the monitor to check the HDD, The instructions given on the guide are clear, I just misread them. Second time around I didn't remove the monitor.
If you have to replace the hard drive I would recommend not fully removing the monitor. I used a pair of thick socks to keep the monitor angled upwards and this allowed me ample access to remove the HDD and install the new one.