When my original weak sprag finally gave up the ghost. I KNEW what it was by the sound when I hit the starter. It made a god awful racket.... whizzing and clacking. Then , the next time I hit the starter it was fine. And it might have been fine for the next few starts. But then it would do it again. Soooo, knowing what was going on, I just went into that left side cover and took it out. Separated the gears that the sprag is housed in. And sure enough a few sprags fell out of the cage. And ever since putting in the new beefer spag, I have had no problems. The point is...... you should be able to tell by the sound, there is no mistaking it. AND, you can not tell for sure without visually inspecting it . Which involves removing the cover, the primary chain and etc. Soooo.... It takes a LITTLE bit of work, but not much ! To be sure. Because it may SOUND ok for a few starts, but then you get the noise again.