Epson Endeavor WG - Manual (Page 105)

4. Position the power supply cable connector so that its notched
corners line up with the notched corners of the drive’s
power supply connector, as shown below. Make sure the
holes fit over all the pins and then push in the connector.
diskette drive
notched corners
hard disk drive
notched corners
Caution
If you do not align the cable connector correctly, you could
severely damage your drive when you push it in.
3-28 Installing and Removing
Drives