I had the pro tournaments with the auto stops and used a retriever. I do not remember what make they were, but they had a large opening for the bead to pass through. Even then, I still had to be carefull because it would not always pass through the retriever correctly and I would unspool the cable on the reel if the bead hung up on the retriever while sending it down. Care also needs to be taken with bring it up also because it can catch and will jam up at the pulley at the end of the rigger.
To prevent the bead from moving up and down the cable, I puta crimp above the bead also. The problem with crimps, is that it makes a weak spot in the cable. If the cable is going to fray, it will happen at the crimp. Some people are using a speed bead with great success in place of the crimp.