either
the fill valve is running and water is draining into the bowl via
the overflow tube in the tank or the flapper is bad (or foreign matter)
and it is allowing water to escape into the bowl through the flush valve slowly...causing the
tank to drain and the fill valve to run every few minutes or so. start by inspecting/cleaning or replacing the flapper and hopefully that will do it because a one piece toilet flush valve
needs a special wrench,to remove it, that you use with a ratchet. If you buy a new
flush valve, it comes with the wrench (glorified piece of plastic) and
is not too difficult to get the flush valve out. you can get a replacement at http://www.plumbingpartsdepot.com/ They do mail order, too. All you need is the
toilet type - a four digit number embossed in the tank starting with a
2. hope this helps but if you need anything else just ask:)
https://www.youtube.com/watch?v=FlJ3UQlkEdU
First you will need to obtain the kit or parts necessary for replacement, compare your parts to your existing before doing anything, you will need your model number and if you had a picture more help could be offered. Begin by turning off the water supply to the toilet, keep a small bucket handy to catch the water, disconnect the supply line at the toilet if your are doing a complete replacement. If its only the handle again a handle kit will need to be obtained for your specific model no need to turn off water but keep in mind your exact handle or button placement. When you have the correct parts its just a matter of remove and replace and take photos of before so you can reference what goes where if you get sidetracked.
if you flush and the water continues to run into the bowl the it is the flush washer that needs repalcing
If that water shuts off and the cistern fills and then continues so that it flows down the over flow pipe into the bowl the it is the water inlet control washer that needs replacing
