Figure 8 shows a common type of flush valve for a low tank. Probably no other plumbing in the home needs attention so often. It is under water and subject to fouling and neglect. The hollow rubber ball gets out of shape and fails to drop squarely into the hollowed seat. The handle and lever fail to work smoothly or the lift wires get out of plumb, causing the ball to remain up when it should drop to its seat. To remove these difficulties, stop inflow to the tank by holding up the float of the ball cock or supporting it with a stick. Drain the tank by raising the rubber ball. If the ball is worn, out of shape, or has lost its elasticity, unscrew the lower lift wire from the ball and replace it with a new one. A 2¹/₂-inch rubber ball costs about 25 cents, and a new one should always be kept in the house. The lift wires should be straight and plumb. The lower lift wire is readily centered over the center of the valve by means of the adjustable guide holder. By loosening the thumbscrew, the holder is raised, lowered, or rotated about the overflow tube! By loosening the lock nut and turning the guide screw, the horizontal position of the guide is fixed exactly over the center of the valve, these adjustments are very important. The upper lift wire should loop into the lever armhole nearest to a vertical from the center of the valve. A tank should empty within 10 seconds. Owing to lengthening of the rubber ball and insufficient rise from its seat, the time may be longer than 10 seconds and the flush correspondingly weak. This trouble may be overcome by shortening the loop in the upper lift wire. A drop or two of lubricating oil on the lever mechanism makes it work more smoothly.