Take a look at the diagram: You are about to add the two jumper wires highlighted in red.

Prepare your Atari 1050 on a clean surface. Put a towel on top of the table to prevent scratches to the unit.

Remove all 6 philips screws on the underside of the unit

Flip the unit back on its feet and carefully remove both the top and front cover as if they were one single piece. Be gentle: This plastic is over 40 years old.

Place the drive in a way the SIO connectors are facing away from you and the front panel is facing you.