Lie down and place you back against the padding.
Gripping the handles, crunch forwards.
In a controlled manner return to the start position and repeat.
Using the arms to pull the weight forwards.
Lower back coming off of the back padding.
Rushing repetitions.
Position yourself so that your lower ribs are aligned with the rotation axis of the machine. Then select the appropriate foot rest and grab the handles evenly.
Start by tensing your core and curling your upper back forward as far as comfortable, then retreat back to the starting position. Ensure that your upper back remains in contact with the padding during the crunch. Repeat for the desired amount of repetitions then gently rest the weights.
Avoid rushing repetitions or pulling the weights with the arms.