What are the signs of 'Groove Dishing' and how does it lead to ring ejection?

Groove dishing is characterized by the groove wall becoming angled rather than perpendicular to the shaft axis. This is caused by a thrust load exceeding the groove material's yield strength. As the wall deforms, the spiral ring begins to twist ('dish'). The radial force component, which normally keeps the ring seated, now develops a vector pointing out of the groove. If the ring's angle exceeds approximately $7$ to $10$ degrees, it will lose all grip and pop out. Engineers should look for a 'shiny' wear pattern on the outer edge of the ring as a precursor to this failure.