I'm glad to hear I'm not the only one that can't figure this out. I do have an update. When I went to my SM center I did not bring the part number from the service manual because Jenny said no database exists to make use of it. However my SM center said they did indeed have access to a database and if I had brought the part number they could have used it. So I called them back just now with the part number to see if the belt they sold me is the right one. They found a different belt which supposedly replaces the 60020. I ordered it but since it's special order I can't return it if they were wrong. That annoys me. This new belt is 14 1/4, the same as the 2 that came with the machine that were too big. But there's a difference between nominal measurement and actual measurement. Like a 2x4 is a nominal measurement but the actual lumber is not that size. So I'm hoping that this 14 1/4" special order belt is a nominal size and the actual size is smaller. What a pain.....