Bear with me and you'll have an awesome little bad ass.
Now what you'll need:

• [HftD] Hailstorm
• Screwdriver
• Something sharp (in my case, a box cutter)

Now remove his arms completely from his torso. In order to do that you need to remove only this screw on both arms:




Then we open the shoulder, which is this:







(The above three images were supplied by Radicon member Methusalen. ~Superquad7)




With that picture you see what we’re going to do. Pop off the brown treads, and cut out the sunken part following the hole you see in the previous picture.

Make sure you level the area around the screw hole where the shoulder joint will pass:




Now, we’re almost done. We simply need to make a little room for the shoulder piece to slide smoothly:




At this point, you need to slice that small block between the two wheels and the corner under it next to the point where the shoulders fold.

And that's it! Piece him back together.
We went from this:




To this:




And, yes he still transforms [properly]!