My Dudley Vantage Cistern has just stopped flushing. It is the sort that has a pneumatically operated flush & previous failures have been due to the air hose coming off. However this is not so this time as I have been in & replaced the hose "just in case" The cistern itself is full of water & depressing the float adds more water. I suspect the problem is with the very end of the air tube as when I press the flush button I can hear a bubble at the bottom of the cistern, but cannot see, & have no info on what should be attached to where or how that end opereates the flush. I have tried the Dudley website for a diagram but can't find one. I am reluctant to try taking the unit apart with no info. I hope one of you professionals can enlighten me Many thanks.