I love how iRobot can move and charge. However, there is a significant drawback in the design of the charger. Sometimes when the iRobot isn't properly aligned, it will rotate back and forth on the charger to improve contact. This will break the clips holding the charging clips in the charger, preventing them from staying high enough to hook the contact onto the iRobot. They break because they are held in place by a screw in a piece of plastic with a hole in it. The plastic just breaks off. This happened to my charger and then I found a friend who had the same problem with the charger. The only way out is to buy a new charger, which isn't cheap.