Epson EL 486UC - Manual (Page 87)

4. Align the hard disk drive so that the cables lead toward the
diskette drive bays and the four screw holes on the base of
the drive are above the four pegs, as shown below.
pegs
5. Gently lower the drive over the pegs. When the pegs are
inserted in the screw holes on the base of the hard disk
drive, the drive will not move from side to side.
Note
If the drive isn’t seated correctly on the pegs, you may
not be able to close the cover all the way.
Installing and Removing Drives 5-9