Epson EL 486UC - Manual (Page 85)

6. Turn the drive and the mounting bracket over, then slide
the slots in the mounting bracket under the tabs at the base
of the computer until the tabs hold the bracket in place.
Note
If the drive does not fit within the internal bay, you can
move the mounting frame toward the power supply and
align only one set of the slots on the mounting bracket
with the tabs on the computer.
7. Secure the mounting bracket with the retaining screws.
4-12 Installing and Removing Drives