XRAY - Model racing cars

As part of a holiday rebuild for my 008 (about 6 months old), I disassembled my ball diffs to service them.

When I removed one of the axial bearings [1], I noticed that one of the balls had fallen out of the race. On closer inspection, the reason why the ball had fallen out was that it had broken in half.

Has anyone else seen a ball failure like this?

Is this something I can expect to see as part of fair wear and tear, or could this be considered a manufacturing defect?

This is the first time I have opened the diffs since new, so I don't know how long the ball has been broken.

[1] 930138 - Carbide Ball-bearing axial F3-8 3x8x3.5


Roy...

That happened to me once. I couldn't get the diff to feel smooth even after flipping the diff rings, took the thrust out, and saw what you saw. I replaced the thrust ($$$) and it hasn't happened since.