Product review (5 stars): WOW!
Looks like the engineers actually must have *heard* the complaints from customers about the wheels falling off.  The replacement hubs are completely redesigned from the ones on the original wire rack.  The old ones had a small clip which eventually weakens and allows the wheels to fall off.  The new ones have a full heavy clip which embraces both sides of the axle arm. I don't see the wheels falling off the new design. Kudos to the engineers!