Bookcase Trouble

With the bookcase delivered, I immediately began assembling it. It was now a familiar process for me as I have done it with two other same bookcases a year ago. I found that at least five shelf boards are so bent as to require radical corrective works. They are under heavy things to let them remember the original shape. Though I got three extra shelves this time, those bent ones canceled them out. While my books, CDs and DVDs, which were already on the shelves, are more evenly and lightly distributed, the hope to place other things on any of the three bookcases is dashed. They remain where I put them on, that is, on the floor.