I have a reasonably new WC (B&Q about 3 years old) which is push button operated, with one of these diaphragm type valves. Recently it has started filling very slowly - about half an hour to fill. I took the diaphragm out and put it back again, and it worked ok first time then slow again since then. I did notice a tiny split in the diaphragm. Would this cause the problem or is it something else?
Cheers