feedback Exact same thing happened to me..
TWICE. In less than a month. Each time happened during tightening down my boats. After the second one broke, I took the old ones apart, and the reason was obvious. The galvanized pipe that runs up inside the black cap does not go all the way up. It only went about a half inch or so, so there's not much resistance when your pulling it from the side (when you're tightening your boats.)

My solution was to replace the pieces of galvanized pipes with longer ones that went all the way up into the cap. This involved cutting to length and drilling a hole through each end - one for the hinge pin on the bottom, and one where the rivet goes that holds the cap in place. I wasn't able to rivet the new version, so I used a screw post: Lowes has them.

Was this more work than I really wanted to do? Absolutely, but I'd already got a deal on another pair, and I didn't want them breaking again. Plus, poorly designed stuff just pisses me off. All they need to do is use pipes a couple inches longer, and problem solved. Since then, I've had no troubles, and I regularly carry between 4-6 boats on them. Word of caution, if you use a chop saw or bench grinder like I did, do it in a very well ventilated area. Galvanized metal gives off some really harmful fumes when it's heated.

Good luck,