Epson Endeavor - Manual (Page 101)

4. Position the power supply cable connector so that its notched
comers line up with the notched comers 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
hard disk drive
notched corners
Caution
If you do not align the cable connector correctly, you could
severly damage your drive when you push it in.
3-28 Installing and Removing Drives