Thanks for the offer!
I have treated all contact points with ProGold, a contact enhancer, and tarnish and oxidation preventer to ensure your light will attain maximum brightness. After a year of use, you could reapply the treatment, putting a little in the threads of the tailcap, and in the contacts of the battery carriers if you want.
ProGold treatment prevents oxidation of the contacts and tarnishing and they remain performing well for years.
In addition, every two or three months the tail cap threads should be cleaned with a rag, to remove the black residue that accumulates when two aluminum surfaces rub together.