I'm having trouble fixing a leak. My toilet occasionally leaks from the handle. The float cup stays emerged under water as the water continues to rise.
Never does the water reach the top of the overflow pipe. It stops filling at the handle level and then slowly trickles through the handle hole and down the tank to the floor.
I checked the float cup and it seems to be sliding up and down just fine without sticking. What can I do?

Must be a replacement flush valve assembly as the original manufacturer usually sets the overflow tube so that the water will overflow the tube before it overflows the toilet handle.

The flush valve should be cut down so that water will flow into the overflow pipe before it will flow out handle. When I run into this I have a mini hacksaw that I use to cut the overflow tube below handle level. You MUST hold the lower part of overflow tube well while cutting... cut slow and easy and will be fine (can use just a hacksaw blade too)... and do not cut too low... just about a 1/2" below handle or so.

Further, I think it is time to replace that fill valve assembly. Look at picture (borrowed from speedball1...if I remember correctly)...this is what I would replace with (called a fluidmaster toilet fill valve...fluidmaster 400A...I think. Available at all home supply stores). You simply shut the water supply to toilet, flush toilet, loosen water supply connector to toilet fill valve, drain water from tank (use sponges for last bits) loosen fill valve nut outside tank, and then remove old fill valve. Replace with new valve as per instructions, hand tighten nut plus 1/2 turn or so, reattach water pipe to fill valve, attach water fill tube to overflow pipe, turn on water, tighten packing nut at shutoff if dripping, adjust height of water, then flush and test. Water should come to about 1/2" to 1" below the overflow tube when shuts off.

Lots of info... but not so hard to do really. Just seems to me that although float seems to work up and down something wrong with fill valve if coming up and over to handle. TRY these things.. see what happens.. let us know if you need more info.

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