I used to repair and upgrade all of the computers that we use in our classrooms but I switched to Mac Minis when they first came out because the fit much better in our equipment racks. After I broke one of the teeny-tiny plugs on a Mini and discovered how hard it was to buy these parts I stopped doing my own repair work. Two of our Minis had dead hard drives and were old enough that it wouldn't really be worth it to pay to have them replaced.
I found a couple of working laptop drives in my store-room and swapped them in after watching the ifixit video a couple of times. Hard drive swaps worked without any trouble. Second one went much faster than the first and I am sure any I do in the future will be even faster.
There are two tiny connectors that the spudger, a desk magnifier and a good pair of tweezers or needlenose pliers really help with. The spudger is much better at prying up the side of the audio cable clamp than a metal tool. Makes it easier to do this gently without breaking it. The tweezers, spudger and magnifier make it much easier for someone with aging eyes like mine to get the hard drive heat sensor cable back into its jack the right way.