Sanyo MBC-550 Series User Manual page 292

5) Place the second drive next to the existing drive.
Compare the two; they both should look the same. If
they do not, turn the second drive over. The bottom of
the second drive has a circular drive motor; it looks
like a turn table on a phonograph. This side should be
facing down.
6) Carefully turn the drive plate, with both drives on
it, over. Align the second drive to the screw holes,
and screw the plate onto the drive.
SECOND DRIVE
DRIVE PLATE
6-7