At some time throughout its life and use, the chances are that the toilet will refuse to flush. You think that it will last a very long time, but you can bet that the one time you want it to flush it wont, no matter how many times you try. Below is some guidance to checking and replacing your flush:You should in the first instance, try giving the cistern and flush handle a good thorough visual inspection just to see if there is something that can be seen as obvious. Finchley Boiler Repair can inspect plumbing and also diagnose and repair problems. Once done with no real result it will more than likely be down to a component failure of something a little more closer to the water outlet. Most likely could be failure of an item called a diaphragm washer that fits under the siphon unit.Find and Replace:1). Isolate the water supply to the cistern and empty it of all the water by flushing. Remove any remaining water from the cistern. Take the siphon from the body of the cistern (it might pay to take photos as you continue the task). 2). Unhook the linkage to the lever arm, if the arm of the float operated valve gets in the way, you may need to remove this also. With the siphon removed you will now be able to see beneath its base and see where the perished diaphragm washer sits. Finchley Boiler Repairs can take on any plumbing task.3). Remove the hook from the shaft that pulls the diaphragm, it should allow the diaphragm housing to drop from the base of the siphon. Fit the new washer and fit the parts back in reverse order (check any photos you took). 4). Restore the water supply and check for any leaks. All of the jointing washers need to be in a sound working condition, if they are not, put some PTFE tape around the joining parts (not on the threads).