We received a PowerTap wheel for service.
It wasn't a rebuild or truing job.

↑Can't photograph the rim, sorry about that.
Also, this is the image after the repair.

The customer mentioned over the phone that "the shaft has play," but
it wasn't lateral play—it was vertical play.
The left bearing had come loose, and the hub was wobbling fan-shaped around the right side as an axis.
This was bad news.
The cause was that the left bearing had fractured.


The broken retainer ring and bearing balls had fallen inside the hub and
stuck to the magnet. Yikes!
（In the image above, the balls have been wiped away and removed）


The inner race of the ball bearing was on the shaft,

and the outer race of the ball bearing had become press-fit into the hub body.
Getting this out was extremely difficult.


↑That's it.
The bearing needed replacement, and we ended up using our very last one in stock.
I'll need to order more.


The usual.


Getting to this point took more effort than I'd expected.
The customer noticed the hub problem while riding on a stationary trainer,
and I wondered "maybe the stress from the fixed roller on the axle was significant?"
But apparently they also use it for road riding, so that probably wasn't the cause.