Looks like there is a stack of sticks above the olive baskets, so those sticks can be removed or added as the pressing continues. When pressing is finished, if all the sticks are removed, then the lever can rest on the tree and be clear of the olive baskets. It would switch from a class 2 to a class 1 lever, and the stone would be lifting the lever end up and out of the way.
Looks like there is a stack of sticks above the olive baskets, so those sticks can be removed or added as the pressing continues. When pressing is finished, if all the sticks are removed, then the lever can rest on the tree and be clear of the olive baskets. It would switch from a class 2 to a class 1 lever, and the stone would be lifting the lever end up and out of the way.