You do not need a service manual in order to work out how the floppy drive can be replaced.
If you're needing to replace the floppy drive ( and you have a suitable spare floppy drive for the purpose ) then you may notice the floppy drive inspection panel on the machine base.
This user removable panel facilitates floppy drive removal without having to a resort to a complete front panel removal.
If you do need instructions to open the top panel for some other reason.
Then look in the VGA install instruction which can be downloaded from the yahoogroup MPC3000 forum files area.
Members only.
http://launch.groups.yahoo.com/group/MPC3000/files/
The document is titled: "AKAI MPC3000 IB-CRT Video Output Board Installation Guide.pdf"
Rohan.