I /dl him as well. I'm using the 4.7 (the latest I'm guessing) and your shoulder texture appears just fine. I checked your activated inventory and such just in case but it is in fact activated. After thinking about it for a few minutes...
I have one suggestion. Check your customs folder with your name on it and see if the joint texture is in there just as Skul said. One thing that I came across that caused problems was if there was a conflicting texture in either the uke or the tori customs folder as well. Try deleting the texture from your customs folder and see if there's anything in those other two places. Re-download yourself and see if it doesn't appear again. c: