Epson EQUITY 386SX/16 PLUS - Manual (Page 148)

Align the connector with the socket so that the row in
the connector with the blocked hole lines up with the
row in the socket with the missing pin, as shown below.
Make sure the holes fit over all the pins and then push in
the connector.
Caution
If you do not correctly align the holes with the pins,
you could severely damage your hard disk drive when
you push in the connector.
2. Place the hard disk drive on top of the subassembly with
the mounting plate facing up.
B - 1 4
Installing and Removing Disk Drives