It looks like 1 1/2 " above your arrow is a high stressed area, not quite a hinge but looks by the pic that you need to scrape above that area. You stated you allready knew about the upper limb so no need to comment there but see if you see what I do in the picture. Look just above the hand in the pic. #006. Looks stiff between the two kinks. Happy Thanksgiving and God bless.