Stand a step ladder under the Craftsman garage door opener motor head. Find the down-force adjustment screw on the opener head. The force adjustment screws are by the wire terminals. Some models have them clearly visible, while others might require removing the light lens to access the screw. Simply squeeze the top of the light lens and allow it to hang from its lower hinge.
Turn the down-force adjustment screw a quarter turn counterclockwise with a flat-head screwdriver to decrease the down force. To increase the down force, turn the screw a quarter turn clockwise.
Go to the garage door with a remote control for your opener. Press the button for the remote to operate the garage door. When the door is moving down to the closed position, grasp the door when it reaches the halfway point. The door should reverse with little pressure.
Continue making adjustments and testing the door until the door closes without reversing, but reverses when slight pressure is placed under the door.