The iMac would randomly shutdown over a period of two months and would require the power cable to be unplugged and plugged back in just to turn it on. As time passed it became more frequent until one day the poor iMac could not be roused. Suffice to say, I performed the appropriate healing rituals, prayed to the computer gods, and gave a blood sacrifice all to no avail. Thus, I resorted to iFixIt.
The process went well using the hard drive replacement guide from ifixit and took about 1.5 hours to complete. I was being extra cautious and decided to blow out all the dust bunnies that had moved into the computer over the last 4 years (the poor bunnies are now looking for a new home in case anyone is interested.) Once it was reassembled the computer is now running better than ever. Seriously, my bluetooth devices actually stay connected, which seems odd since this is a power supply repair, but I wonder if the old power supply as it was dying was creating some sort of RF interference that would cause the bluetooth to drop or work intermittently.
Don't leave the suction cups on the glass any longer than necessary for the removal. They will leave a goo on the glass that is very difficult to remove. And NO, the goo was not there prior to using the suction cups (keep it clean folks ;-). Also, the T8 screws were on very tight and with the iFixit kit I could not remove some of them since the handle for the driver was too small for my hands. I had to find a driver that had a larger handle to get the torque necessary to loosen the screws. Make sure you have a large table to work on, a few large towels to lay the lcd and glass on top of, and some nice clothes to clean the lcd and glass with as well. When you are putting the iMac back together I would connect the LCD power to the power supply before screwing the power supply back in. Just get someone or something to hold the LCD screen up while you are screwing the power supply back in.