Also, I have watched every Mullen documentary out, and in atleast one of them (cant remember which) he talks alot about how he got injured and how he overcame it.

His approach to learning and trying things is to try and isolate a single body part that is throwing off the trick, and only concentrating on changing that one body part at a time until if feels right before moving on to the next body part if the trick still doesnt work / feels uncomfortable.

I was trying this recently with fakie (90 pivot) to 5.0 stall back to regular on QP, everytime I locked the truck in a would step off backwards, after watching on film I could see that it was my right shoulder (the one in front as I was fakie) was swinging too much so I couldnt stop its momentum. Pulled the shoulder in and it felt alot better, something I wouldn't of thought of trying without hearing his method...