IBM 5155 Manual To Operations page 266

40
Place the system unit so the rear faces you. Use
a S.S-mm (7/32-in.) open-ended wrench or a
3-mm allen wrench to loosen the diskette drive
mounting screws on the right side (Do not
remove the screws from the threaded screw
holes).
Loosen
Mounting
Screws
4-38 Option Installation