Abstract: An anvil assembly having a housing and two rotatable inserts with flat upper surfaces against which the heated shoes of a package sealing machine may press a covering sheet onto a plastic package tape. The inserts have a limited range of rotation so that they automatically align themselves to be parallel to the heated shoes when they are contacted thereby. This rotatable insert feature obviates the need for precise, laborious alignment efforts. Alternatively, a pair of rotatable blades are pivotally attached to the shoes and act against a fixed anvil surface, thereby automatically aligning themselves to be parallel to the anvil surface.