Instruct: Classify Amazon reviews into positive or negative sentiment
Query: poor jar design

The blade mechanism in the jar has a shaft that comes through the bottom of the jar and is held in place by a nut that is reverse threaded. When the blades start spinning, they spin in the opposite direction as the nut tightens causing the nut to come loose and the contents inside of the jar leak on to the base motor unit. Despite trying several times to tighten this nut, the power and the speed of the motor loosen this nut each time. Very poorly designed.