You might want to check out Joe Tucker's Third Eye Stoke Trainer. It really is amazing for such a simple looking device. The Third Eye will force you to sight centre ball and the arms give you valuable feed back by telling you if you are steering to the left or right. It also helped me with a slight twist in my grip, I didn't really have to much of a problem with finding the center of the CB but it gives great feedback for a few posible stroking flaws.
Joe's Laser Trainer also helps sighting, line up the lasers on a straight in shot and then you can find the proper sighting picture. Joe talks about this in the into to his Laser Trainer video on his site. I've also been told about his new magic eye that I believe is to assist one in alignment. Joe has some of the most unique and helpful training tools out there, check them out!