how do i know if my comet drive is a tc 88 or 20 series. Im thinking its a tc 88 cause i just bought a three quarter inch comet belt and it is wider then the brass bushing. Shouldnt the belt be same width as brass bushing. When i put cover on driven and tighten it down, it grabs belt and wont let go. Is 20 series a wider unit all together? getten frustrated with all this different size belts. thanks