How to Remove a Cap From a Fluidmaster 400
Installing or servicing a Fluidmaster 400 fill valve requires removing the top cap. When installing the Fluidmaster 400, it is necessary to remove the cap to flush the system. If you have a slow fill issue, remove the cap to determine if the seal requires replacement or clean away sediment that might be building up inside the fill tube. Removing the cap from a Fluidmaster 400 is a straightforward process requiring no tools. The cap connects to the float arm and hangs safely out of the way once you remove it from the top of the valve.
Turn off the water supply valve behind the toilet. Rotate the valve handle clockwise until it stops to turn off the water supply. Lift the toilet tank lid off the toilet and set it aside on a flat surface.
Grasp the top of the float with your fingers and hold it up slightly. This also lifts up the float arm that connects to the float and the Fluidmaster 400 cap.
Press down on the cap slightly with your free hand while holding the float. Turn the cap counterclockwise until it releases from the Fluidmaster. The cap will hang over the side of the fill valve once you remove it from the top.