On the Green Power/Green Life machines, why do you need to use an outlet knob? (either normal or fruit attachment) I didn't use either knob for our first batch of carrot/apple juice, and it turned out just fine. Why is the special attachment used for soft fruit?

The attachment for fruit (green) has a softer spring tension to allow the SOFT fruit pulp come out of the machine. If the knob is not installed the pulp may come out before time.. (thus you will have wetter pulp and less yield of juice). The normal knob (white) has a hard spring tension to allow hard veggie fiber- carrots, greens, etc to remain in the machine so it is still juiced, and will come out dryer. If juicing apples/carrots, use the white knob, and put in the apples first then the carrots (the fiber in the carrots help push the soft fiber of the apple through the machine)