the prop rods are not very useful. they are unstable, and in my opinion contributed to the leaky tank hinge problem that the older models had. but if you really want one, post up in the parts wanted thread. i'm sure someone will have one for you.
While the rod may put the kind of stress on the hinge that promoted failure it isn't the rods fault entirely.
The cause is as simple as two omitted small mig welds.