Why are the modern filling valves so complicated? In ours downstairs there are a number of complex plastic parts, O rings and a rubber or plastic diaphragm. It emits a loud noise when the tank's filling, I've tried dismantling the valve and cleaning it but it still emits a high frequency noise. I've already replaced it with a new one 3 or 4 years ago but now this one's started. I've taken it to pieces to clean it but there was no noticeable muck in there and in any case it's a sod to put back together. Looks like I'll have to go and buy a new one. I love the old fashioned type with a brass piston that forces a small washer against the inlet to shut it off, dead simple and reliable, our local ironmonger sells them but they won't fit because the inlet is underneath on the new ones but on the side on the old type. We've got one upstairs and it's not given trouble in 18 years I do wish manufacturers would not design things more complicated when there's no need.