I'm not really a fan of any of the GW dragon designs, they all seem to be balancing on their tails. I much prefer what Alexey has done with the Polar Fox Wyverns, they are in much better positions IMHO. Hence me chopping and changing this one a bit.
The arms are not pinned just glued and sealed with green stuff, but I did pin the back leg and the wings would have joined the back in a much higher position where as I wanted them to look like the dragon was gliding into a ground level attack. So these have both been pinned to each other and then pinned to the dragon's back, then sculpted quite a lot of green stuff to cover up the sizeable gaps.
I had to cut about an inch and a half off the tail, so I've drilled into the main tail, inserted some pinning wire in there which I bent to make a bit of movement in the tail, I then built up rolled green stuff over the wire to make the tail.
SW - it does balance pretty well, I'm going to mount it on a Polar Fox clear base and to do so I've had to cut a chunk out of the dragon's belly. I did check the balance on the right style of base (now ruined by green stuff and superglue fingers!) but as I've ruined that one I've had to add some onto my last Polar Fox order!