I heard this pop and then....

It sounds as though you will need to take it apart to inspect it. I'm still wondering about the axles not being in all the way.

I'm assuming you have the chunk out? Can you post some pics of the axle shaft ends? Pics of the splines in the carrier? Pics of the axle bearings?

Just for grins, maybe someone can spot something. If you can do that before tearing into anything it might help.