your lhs should have one but the trinity one will only line the brushes up to each other. the brush will actualy cock to one side due to the arm spining in the can. so just use the bar that go's in the brush hoods.
to align the hoods-
take a old set of brushes and file them flat on the face that comes in contact with the arm. then take a sharpie marker and blacken the face of the brush. while working on one side of the motor (pos or neg) spin the motor for like 5 seconds with a 4 cell and then see were the brush is wearing. loosen the screw and spring post and adjust the hood so the brush wears down the middle. then repeat on the other side of the motor.
you should then recut the motor and install new brushes. plus since the motor will have the whole face of the brush on the arm its power and rpm will go up since its getting more juice from your batts.
this is how i set up my motors right after i buy them and it lets me hang with the fast guys at socal, now if only i could work on my driving skills