And if you revise it, please include my idea of making a cross brace on the lower two shafts that hold the wheels, making it rigid sideways.
When you tip over, and you start rolling on 4 wheels (someone with a monstertruck knows what i mean.. ;) ) one sideimpact on the wheelie bar will instant destroy it.
Perhaps the flex that was in it, did caused binding on the shaft inside the shock, resulting in what happened. A shock doesn't bent when it is pushed in straight. (or the oil, that was used in it ws to thick)
Since I bend one axle an at least 3 pillow balls (titanium ones) I decided to go for the 8mm axles and the steel pillow balls.
I hope this stuff will last longer....