1 - 3 uren
The 1Tb Seagate in my Mid-2011 looked like it was developing bad sectors and caused some unrecoverable boot issues. I think the machine would have qualified for the 1tb replacement programme but the programme was already closed...time for some DIY and an opportunity to upgrade too :)
Taking apart my baby wasn't a decision I took lightly but the iFixit guide was comprehensive and very easy to follow using my iPad as a companion. Also the iFixit Dual Drive kit and toolset was good quality and easy to use. Disassembly and reassembly took maybe 1.25hrs and the iMac booted back up first time no trouble :)
I took the opportunity to replace the 1Tb for a 3Tb (Seagate again, to avoid fan issues) and also added a 250Gb Samsung SSD as my OS boot drive. I put 'Yosemite' onto the SSD before starting using CMD-R and a SATA/USB Dock. I also formatted the 3Tb so it was ready for immediate use in the same way too.
There are a couple of recommendations :-
a) A can of air duster would be a great addition your 'arsenal' of tools - it's surprising how much dust the fans had drawn into my machine....and a handy can of air duster would have been much more wieldy than a hoover nozzle.
b) Get the screen cleaner before you start - I was too eager once the iFixit kit and the new drives arrived. I ended up leaving my glass off overnight so I could make a shopping trip for screen cleaner in the morning.
c) When you get to the end of disassembly and are ready to rebuild, re-read ALL the steps backwards. The guide says something like start reassembly at step 27 but if you miss 28 + etc you risk missing a vital process such as screwing the logic board back in. I worked my way backwards one step at a time and am glad I did...It's hairy enough taking your machine apart once, you don't want to be experiencing the panic of a 'dead machine' because something in the later steps has been inadvertently skipped and then have to disassemble the machine again ...this time in a (slight) panic.