Apparently this is a wear out item - there is a retaining strip in the track that holds the ball bearings in and it will fail over time, releasing a small army of ball bearings into your dishwasher. Not a great design, IMHO, but easily fixed.
Required me to pull the dishwasher cabinet out of the opening and access the fasteners from the outside - literally a 10 minute job. 1 out of 5 wrenches on the difficulty scale.
If you can hang a picture without smashing your thumbs or breaking your picture frame you can handle this replacement.