Down through its life, the altarpiece has undergone several important alterations and no longer conserves all of its original figures. The figure of Saint James the Apostle and that of Saint Anton on the extreme right of the altarpiece did not form part of the original group of figures. Both figures have been altered to fit into the altarpiece; the first by reducing its height and the second by altering its rear since it was originally probably a much bulkier figure.
The frame of the altarpiece has also lost its wings, tracery border and part of the architectural decoration. We can also see whitish stains in several places that have been left behind after microbiological attack. Xylophagous insect attacks have resulted in considerable loss of volume, particularly in some parts of the figures such as hands, books and feet.
Numerous interventions with their wood pulp and plaster fillings have altered the shape of original figures. The figure of Saint Anton (to which someone has nailed a cloth to cover its rear) has been completely polychrome redecorated and parts of the polychrome decoration of Saints Peter and Paul have been re-gilded and re-painted.