First things first,,,, What caliber have you got it mounted on ?
The Nikko Nighteaters are not a high end scope, and not usually recommended for something with decent recoil.
I have heard some shooters say that they wouldn't use one on anything above a .22 rf
I've also heard some say that they won't hold a zero reliably.
Having said that, I feel kinda lucky cos I got one of the early ones ( a 6-24 x 56 ) and put it on a 22/250 with marvellous results.
It always held zero (even after my feet slid out from under me once on a downward slope while it was across my back)
Much to my disgust it hit the ground before I landed on top of it myself.
I used it on the 22/250 for 5 years, before I took it off and remounted it on a .22 rf
Still using it today, and its good.
Maybe I got a good one,, but as I said, they aren't a high quality scope.
With yours, I'd definitely take it straight back to the dealer without attempting any "repair" job.
Cheers,
I do not fear death itself... Only its inopportune timing!
I've come to realize that,,,,, the two most loving, loyal, and trustworthy females in my entire life were both canines.