The valve seal, also known as a pill rubber, or simply a pill, is a tiny, pill-shaped rubber seal responsible for blocking the path of soda water when the siphon is not in use. The valve seal is located at the end of the valve stem.
The bottom of the seal will deform somewhat during normal use, but this is not necessarily a problem. However, its material will age over time and become stiff, maybe even crack. Replacement is recommended at every maintenance. The underside should be coated with a thin layer of silicone grease.
