Sorry, to be clearer (I can't edit my main comment now), Steps 8-13 are not necessary and Step 14 only partially necessary. Only 2 of the screws in Step 14 need be removed – the one circled red and the lower one marked orange.

This is the usual valuable guide to disassembly. However Steps 8-14 are NOT necessary and create added complication and potential for problems on reassembly. The motherboard can be safely removed with the fan and heatsink attached (make sure to leave the top right 3.6mm fan screw that secures to the motherboard – marked orange in Step 14 – in place). Obviously be careful not to place stress on the fan while it is only held on the one screw but otherwise there is no problem lifting and sliding the board at Step 31. I was able to get at the microphone easily after that and refitting the board was easily done too (making sure cables are not trapped underneath).

I'm slightly at a loss as to why removing the heat sink is deemed necessary unless this guide is based on another where that step is required.

I upgraded a 20GB model with a 128GB CF card. After reassembly the iPod started up fine - I had connected to iTunes to test it while the back was off in case of any assembly errors. As soon as it was plugged in the software restored the system automatically to Untitled iPod and I synced it, apparently successfully. However, when I reassembled it fully I got the folder error on the screen, as Philip Swan found above.

I rechecked all connections and all was OK but the iPod didn’t respond. So I reconnected to iTunes and forced a complete restore. This time once it had restored it said on the iPod screen that it needed to be disconnected and attached to a power-only supply. Once this was done a further progress bar appeared on the iPod screen and then the normal menu appeared. After that it appeared in iTunes as [myname]’s iPod, ready for syncing with playlists, which it did without a problem and the revamped machine is working fine again.

I upgraded a 20GB model with a 128GB CF card. After reassembly the iPod started up fine - I had connected to iTunes to test it while the back was off in case of any assembly errors. As soon as it was plugged in the software restored the system automatically to Untitled iPod and I synced it, apparently successfully. However, when I reassembled it fully I got the folder error on the screen, as Philip Swan found above.

I rechecked all connections and all was OK but the iPod didn’t respond. So I reconnected to iTunes and forced a complete restore. This time once it had restored it said on the iPod screen that it needed to be disconnected and attached to a power-only supply. Once this was done a further progress bar appeared on the iPod screen and then the normal menu appeared. After that it appeared in iTunes as [myname]’s iPod, ready for syncing with playlists, which it did without a problem and the revamped machine is working fine again.

It is perfectly easy to remove the cable if you are careful and observe what you are attempting to disengage. The plug on the ribbon cable goes into the small black socket on the motherboard. Look sideways at the assembly and slide a thin spudger between the top of the socket and the small board that forms the end of the cable. Lever gently upwards to disengage the cable plug. That way you cannot exert force between the socket and the motherboard and you won’t damage the board.

Late 2015 iMac - mine had all T8 screws and 4 along the bottom row

These connectors seem pretty tough to remove until one understands the latch. Each side of the plug are two little sprung tabs (the tab is part of the spring clip which runs down the side of the plug on each side - makes sense once you see the removed plug!). Squeeze them in towards each other and then gently pull the plug from the socket. No great force, or even the spudger, needed once that is done.