Wow, never seen one break. They are generally well made, and although they warn you not to put more than 6 pounds on the rack (I’ve actually stood on mine) I’d say your right it was just metal fatigue from stress over time.
The welding suggestions above should work. You might want to install some kind of block under the rack when you re-install it, that goes from one of the racks rungs to the fender. This would take some stress off the apparent weak spot of the rack when your case is loaded and your going over bumpy roads.
It’s been known for years that licence plates will crack do to vibration (not wind) and it’s a good idea to back them with some heavier gauge metal. [IMG class=inlineimg]/forum/images/smilies/icon_wink.gif[/IMG]
I thought about this too, maybe try something rubber to dampen it. We’ll see, should be able to repurpose something. I also think it’s a wise idea to somehow strap the last rung under the seat to the top of the fender we’re it bolts in. That might be overkill but it’ll bring piece of mind.