We installed three new Ultramax toilets in February 2007. The fill valves on all three leak (sometimes a constant drip, sometimes a sporadic spurt). I have cleaned out the filter (it was spotless) and replaced one of the valves completely with a new one and it leaks also. When they leak, the water comes out of the fill tube between flushes. After a flush when the tank is filling, water usually leaks out of the valve cap before the fill tube.

Any suggestions? Thanks.