It's a game of playing with the scale screws and the pivot...
There are some knives that just can't be centered perfectly because the tolerances are too far out.
The above links provided will get you going in the right direction.
I have had knives that would center but only if the pivot was really tight, regardless of how I played with the scale screws.
I would suggest, if that ends up being the case, that you loosen the pivot to where the knife functions smoothly and then let everything wear in.
You should eventually get to a point where you will be able to center the blade and the pivot will no longer be too tight.