I can't see what you are talking about. A normal 30 series driver will use the same belt as the juggernaut. Inner open, and closed outer diameters are the same. I also don't understand what Chicago has to do with a driven clutch.
Your juggernaut is not missing a piece between the sheeves. When working properly, the springs inside keep the sheeves separated ( very strongly so ) until centrifugal force ( by the engine spinning it ) starts to close them. The 3 legged part you are describing is called the spyder. If you get on the Go Power Sports website I think they might have a video on reassembly. Once again, it's not an easy fix. The inexpensive 30 series torque converter driver is your quickest answer to getting your kart going. ALL existing parts that worked with the juggernaut will work with the standard driver.