Instruct: Classify Amazon reviews into positive or negative sentiment
Query: Engineering flaw

I just attempted to vacuum the carpet and, for the zillionth time, the belt that drives the carpet brush came off. It does this so frequently that it is essentially useless for the carpet. Today's problem occurred when I lightly bumped it against the baseboard. Having fixed it myself many times, I know that the problem is caused by the fact that the metal piece the belt goes around actually tapers slightly in such a way as to invite the belt to slide off. Were engineers involved in the development of this product? How could anyone do anything so dumb? When I was a kid, Hoover was considered to be a reliable product. How times have changed!