Holding the assembly in a vice, you need something to lie in the port of the brake and stick out each side like a wing... then a straight edge on the action hanging out each side like a wing... it is easy to see how closely they are...
Hopefully it is short of being indexed and removing a few thou will line it up... trial and error... 1 divided by the number of threads will give you how much material to remove for 360 degrees.
