Took my tools and installed new back on right side fake wood bookcase that I recently acquired. It had a bad case of the wobbles. Loaded with books it might tilt over at any time. So installed a Masonite back and used my trim nailer to attach it. I also nailed through into the shelves in hopes of giving them more strength. After I reloaded the books I realized the case is about 1 inch away from the cabinets behind. More work for another day. In the future I will replace the backs on all bookcases before I bring them to the library. Then we only have to load books one time.
We still have two stacked bookcases similar to the one that fell Wednesday. I used some leftover Masonite cut into squares and nailed them across the joints on both sides. These are high on the priority list for replacement.