The corners of a book take a great deal of stress and can be damaged while
the rest of the case is still in good condition.
This is another repair that is often handled with plastic tape or purchased
“repair wings.” Applying tape or wings does not repair the corner; instead it
adds a layer of tape on top of the problem.
The adhesive on the tape can seep out or dry up over time, causing the plastic carrier to fall off. That can leave behind a sticky residue that is often impossible to clean up.
If the book cloth has been worn off the top or bottom edges of the cover boards, replacing the book cloth at the corners may not be a wise use of time. You might consider rebinding your book to get the best value for your time invested in repair work.
The next post will show you a method for repairing corners of a hard cover book.