Caution: To get to the internals of this machine, you must get near the CRT. The CRT can be very dangerous if touched and can shock you causing serious and even fatal injury. Please be careful when opening these computers. It is a good idea to "uncharge" the CRT before operating inside the Mac.
Just like the original Macs, you have to remove the outside cover to get to the logic board. First, put the Mac in a face down position and remove the screws that hold the case together (there are four). The screws are Torx screws. Next, pry apart the Mac. There are special tools made for this. There may be a memory board in your Mac, you need to remove this to get the logic board out. Otherwise, you will damage your expansion board. Disconnect the cables from the logic board and pull the logic board out.
Remove the cover. Disconnect the hard drive cables from the logic board, remove the two screws that hold it in place, and remove it.
Remove the logic board and the hard drive. Remove the screws on the bottom of the case that hold the floppy drive in (4 of them), and remove the floppy drive.
Information provided by Doug Brown.