If the information on the endpapers cannot be saved by constructing a new endpaper or photocopying, the pastedown can sometimes be mechanically lifted off the cover board or soaked off in water.
Use a microspatula or sharp knife to carefully lift the fly leaf off the cover board. This procedure works best when the glue under the pastedown has dried and the pastedown is only loosely attached to the cover board.
Some pastedowns can be removed by soaking the endpaper and cover board in water. The cover board must be detached from the text block.
DO NOT IMMERSE THE ENTIRE BOOK IN WATER.
Soak the cover board with its attached endpaper in warm water for no more
than half an hour. The water should release the adhesive, and the pastedown will float free of the board. Before immersing in water, make a copy of the pastedown to be used in the event the adhesive is not soluble in water or the color runs.
Dry the endpaper between blotters. Change the blotters to hasten drying.