The classic teaching for phaco chop and quadrant removal is to embed the phaco probe into the nuclear piece by using a bit of ultrasonic energy. A brief push into foot pedal position 3 gives ultrasonic energy and then the foot is brought back to position 2 to hold the nuclear piece with just vacuum. This works well most of the time, but often the nucleus is too soft and it crumbles on application of ultrasonic energy.
The solution is to simply push the phaco tip into the nuclear piece and then apply just vacuum with foot pedal position 2. No ultrasonic power is given until the piece is brought out of the capsular bag with vacuum and positioned at the iris plane. Because the nuclear piece is relatively soft, simply pushing the tip of the phaco probe allows it to become occluded so that a sufficiently high vacuum level can be achieved. This translates to enough holding power to engage the nuclear piece.
Click below to see the probe pushed into a softer nucleus without ultrasound: