I took my Z1 apart to recently check for power problems - most likely a n AC cable problem.
Consider letting a laptop shop change the hard drive. The cost may not be too obscene, and you can always blame trhem if it goes pooh.
FIrstly, if you want to take the computer apart, make sure you back everything up. If you balls it all up and damage something, at least you will have saved all your files.
DO some research and download / copy all the files from Vaio-link for your particular laptop.
Also, download and read the hardware manual. Thre is a section on adding memory. This will hemlp you get the keyboard off. and access to the memory module.
You will probabaly need to remove the small hinge covers for the screen. More easily done with the screen shut.
Be very careful with any of the ribbon cables. These are very easy to tear, but also they are very easily to safely remove.
Once the keyboard is removed, and you have removed ALL the screws from the underneath (don't forget the ones in the battery bay) you will see that there are a there are a few more screws from the top.
Make a note of which screws come from where as there are a few long and short ones.
The Silver surround is still fixed to the lower case, but a strong fingernail or dead credit card helps (and causes less damage than a screw driver). Be carefull as this comes off, more ribbon cables around.
The hard drive is to be found under the area where your left palm rests.
I cannot advise you on what hard drive to buy. Make sure the hard drive is compatible and voltage supply is ok. The hard drive supplier should give you some advice.
