Well, now - - from the pictures I could find. It appears that when the tines are in a notch - either full up or in one of the two down position - there is some sort of something behind the tines that holds them in the notch. This would keep the tines from moving to the rear and falling out of the notch. I could not find a picture that showed what that something might be - a bar - some sort of lever or a pin???? If it is not obvious on your unit - it could be a missing part or parts.