Well, I registered here because I lost AWD in the 2010 CX-9 GT @ 113,000 miles. I have front wheel drive only now. The t case has had new oil every 30k, the shop (not mazda affiliated) did it the first few times then I purchased the oil pump and started doing it myself from the youtube vids from here. I was using royal purple and always made sure I pumped out and replaced the fluid and made sure it was full, I'm a farm guy so I'm very used to pulling fluid and replacing in odd positions, this wasn't a big deal. The AWD went out, there was no howling, grinding or clunking it just went away. The only relevant thing is the right wheel bearing is going out as well, so some of the t-case noise could have been attributed to that, my wife drives it.
Some other issues:
Both front wheel bearings have been replaced already.
The right rear wheel bearing is going out.
The lift gate ram wallowed out a big hole in the tailgate where the ram connects, not cool. The little arm came loose, wife very upset she can't use the back door as I pulled the fuse after finding the hole. At least the ram won't try to shove through the window though.
So I guess I'm looking for a walk through on replacing the tcase, where to source it and whatnot then I'll address the other issues.
Thanks