Hi I have read over similar problems about this.. my flushing cistern makes a loud noise after flush. I took the entire float arm and stand pipe cleaned put back together but no fix. I read about people say turn washer around but where is this washer exactly? And also about going at some screws but only screws in my one seems to the one to control level of water. I have a bottom entry type valve which is in complete plastic. Any ideas please?

It is either your angle stop or the fill valve has dirt in it. To fix the angle stop: Close it all the way and Open it again. To remove dirt from fill valve: close angle stop, remove top cap of the fill valve, put towel over the open fill valve tube, open the angle stop with your other hand for few seconds, close angle stop, then make sure there is no dirt on upper part of fill valve including rubber washers, reinstall, turn angle stop back on. See if that helped...

You I tried all that but to know help I completely disassembled each part an cleaned also flushed line. I didn't turn washer around though as I was uncertain about where it was? Would it be next be to the seating used (the one I have is a red and has big orifice as its fed from storage tank) there is a black o ring type washer there that sits on it.. its on the horizontal part of the upstanding valve? Only other washer I could see was at the bottom of cistern were the fill valve enters and a back nut on opposite side of it. Do you know which one they refer to when they say turn washer over?