The Very Lonely Firefly by Eric Carle is a children's board book with a flashy last page. There are 8 tiny light bulbs embedded in the back cover that turn on and blink when that page is opened. The illustration on that page is of 8 fireflies with the lights in their abdomens.
The switch for the bulbs is a plastic strip connected to the 3rd to last page; it goes through the next to last page and slides under the last page to operate the lights. This switch quit sliding back into place and left the lights on when the book was closed running down the little batteries.
My friend at the library asked me to fix it.
I pulled the back cover off revealing that the slit in the page for the sliding strip was torn just a little. This gave just enough slack for the strip to bend backward and not turn off the lights. I cut thin strips of plastic tape and repaired the edges of the slit, glued the cover back on and the fireflies now light up when they are supposed to and sleep when the book is shut.