Sychro Band Wear
The best way to assess synchro band wear is to view the band in cross section. It should be domed in the middle and symmetrical, with no groove near the edge and no polished surface. This band, which is from another transmission, fails on all accounts. The right side of the band was toward the gear, and you can see a groove in the edge; it's most easily seen in the part that is held in the vise and is unfortunately a little blurry. You can also see that the top surface is polished. Most important, though, is the asymmetrical cross section. It is a little difficult to see in the picture, but the left side of the band's surface, which contacts the slider, is worn; the cross section is no longer symmetrical, and the center dome has mostly worn off.