Abstract: A machine for installing a foil insert in a container lid such that the insert may be subsequently sealed to the mouth of a container after the lid is placed on the container includes a punch for blanking an insert from foil sheet, and a plunger having a head that emerges from the punch and carries the blanked insert forwardly to the lid. As the plunger advances, a folding arm presses against the tab and folds it over onto remaining or disc portion of the insert, and while the arm folds the tab, retaining fingers of a holding element hold the insert against the plunger head on each side of the tab to ensure that the tab folds at the proper location. Only after the tab is folded over does the plunger deposit the insert in a lid that is supported in the path of the plunger on a lid holder.