The 2400's CPU is on a daughterboard. This makes it possible to upgrade the CPU from the stock 180 Mhz (US market) 603e, to a 240 Mhz PPC 750, or even 320Mhz PPC 750. The daughterboard also contains the cache for the CPU, so upgrading the CPU will also change the cache, usually a good thing.
With all that said, upgrading the daughterboard is a daunting task for the Do-it-yourselfer. There are 34 screws of various types and sizes. It is easy to forget which screws go into which holes (or even if a screw is supposed to go into that hole.) Every screw has a reason, however, so if you get it all back together and you have a few extras, this is not a good thing.
And with that preamble, I now will delve into the guts of disassembling the 2400 so as to replace the CPU daughterboard.
I. Outercase and keyboard.
Click on the thumbnails for larger images.
The first thing to remove are the screw caps. On the piece of plastic above the keyboard, you will see to small circular pieces of plastic flush with the rest of the plastic. Remove these. You can use an exacto knife in an attempt to preserve them. I eventually lost mine. Underneath these caps, are two screws. Remove them.
Above the F3 and F12 keys, you'll discover to small slits in the plastic piece. Once the screws have been removed you can pry up the plastic using these two slits. It helps to fold the screen back, when removing the plastic.
Once the large plastic has been removed, you can take the smaller section out that lies directly beneath the hinge. I'm holding the smaller piece in my hand in the photo.
Next slide the other half of the top (not the keyboard) away from the screen. It should move about half an inch. You can then lift it up. Be careful, as the ribbon cable for the trackpad and button are still attached to the motherboard. These are held in by a standard (to me anyway) mylar ribbon connector. Slide the two ends up and pull out the cable. You can set the case aside now.
The keyboard is held in place by 6 screws. Remove those, and lift the keyboard up. Two mylar ribbon cables attach to the motherboard. Remove them and set the keyboard aside.