Figure 7, A, shows an ordinary compound-lever ball cock to control the water supply in a flush tank. The float ball and the seat washer on the bottom of the plunger are the only parts likely to need repairs. The buoyancy of the float is the force which lowers the plunger, shutting off the water as the tank fills. A leaky, water-logged float holds the plunger up, permitting constant flow and waste of water. A small leak in a copper float can be soldered; but if in bad condition, the float should be replaced by a new one. A good copper, bakelite, or hard-rubber float 4 by 5 inches costs 25 to 50 cents.

Figure 7, B, shows the plunger and washer-holder cap which screws on the bottom of the plunger. The washer should be of soft rubber or leather, because the force which holds it to its seat is not heavy. The cap is thin brass. To replace the washer, shut off the water and drain the tank. Unscrew the two thumbscrews which pivot the float-rod lever and plunger lever. Push the two levers to the left, drawing the plunger lever through the head of the plunger. Lift out the plunger, unscrew the cap on the bottom of the plunger, insert a soft, new washer, and reassemble the parts. The cap may be so corroded and weakened that it breaks during removal from the plunger. A new cap is then necessary, and it is well to have one or two on hand. When putting a washer on a ball cock, examine the seat to see that it is free of nicks and grit. The seat may need regrinding, as explained under compression faucets.