Epson EL 3S/33 - Manual (Page 54)

5. Hold the card along the top corners and guide it into the
connector, as shown below. (If you are installing a
full-length card, insert the front edge of the card into the
corresponding guide inside the computer’s front panel.)
Once the connectors reach the slot, push the card in firmly
(but carefully) to insert it fully. You should feel the card fit
into place. If it does not go in smoothly, do not force it; pull
the card all the way out and try again.
6. Secure the end of the card to the computer with the retaining
screw.
Installing and Removing Options 3-15