To be truthfull, the fluidmaster valves are a pain....if I remember correctly, the float is adjusted by a plastic vertical screw - the top of which easily detatches from the plastic body? A much better one is one made by Torbeck - dead simple and almost foolproof. Mind you, your flush mechanism should allow water to flow down into the loo bowl, rather than through the flush handle! The tube leading upwards from the flapper valve is cut to length to suit the level of water in the cistern if its installed correctly.
John
September 2009