How can I stop filter water leaking from good o-ring?

[Perifractic]

Edit: I solved this by taking to the hand tightener with a wrench.

Hi guys, please see this video: (solved)

I've removed and clean this 1 year old o-ring, and the surrounding metal, greased it, and reinstated it but after a few days it starts leaking again.

Any ideas welcomed!

Thanks!
Perifractic