You can make a SMALL adjustment to the blade centering sometimes by tapping the pin on the side that you want to move the blade towards. IE: If you want to blade to move to the left, tap the pivot pin on that side.
You don't usually get too much movement from this, but it may be enough to center up your blade.
If not, do a search for it. There's a ton on info on here that I don't understand how to link to :)