- Edited
europa - Sorry. I’m getting confused it seems. I’m not sure which o-ring your are referring to then.
If this o-ring is on the “tap” itself (I don’t remember as I’ve done mine a while back), then just add some grease on the surface as it will touch the ball valve. The ball valve moves against it, so it should be well lubricated.
Hope this helps, and hope I’m speaking about the right o-ring.