Epson Apex User Manual page 97

5. Now, insert the card straight down into the slot. Slide the
tab at the bottom of the retaining bracket between the
back panel and the green main circuit board.
6. Once you have the connector pins sitting in the connector
slot, push down firmly (but carefully) to fully insert the
card. If you feel that the connector isn't going in smoothly,
do not force it; pull it all the way out and try again. Be sure
to keep it straight.
7. When the card is properly inserted, secure the retaining
bracket to the frame of the computer with the small screw.
4-6 Installing Option Cards