If you get your fingers wet while serving, the joint is probably tired.

Changing it is very easy:
– Remove the old one by cutting it out with a fingernail or a knife point.
– Put a drop of oil on the screw and the seal then slide it on the screw until it fits into its groove.
– Screw the screw into the valve body for the first time by “passing a small hard weight”, then completely unscrew and take out the screw.
– Remove the small joint chip which cut itself out by “passing the small hard point”
– Tighten the screw fully and check that it operates smoothly and that it does not scratch when opening / closing.
– Here you are again for 10 years!