My rear axle broke too... just as I was putting in the final screws to secure the body to the chasis. It's ridiculously fragile for such a heavy model. I wasn't even being careless. I simply turned the model the right way up to see if everything looked lined up and one of the rear wheels snapped off. I'm not going to strip the whole thing down just to fix that so will glue it and hope for the best. Now that I've finished the build, it's obvious that certain parts have been scrimped on (the hood pins - insanely easy to break, the extremely thin chroming on some of the plastic parts that can be easily scratched with a fingernail, the flimsy steering wheel, and others). I know it's a static display model, but even so... very poor in places.
Let's hope the Leopard tank is a little less fragile, given that that's designed to be driven around!