Wish I had seen this tear down and rebuild before I started my puppet version for my Terminator film. One thing that drove me crazy from the get go was the open jaw and horrible teeth. The stock teeth will work, but closing the jaw is a little more difficult. I broke the whole skull down into separate components and trimmed the "pneumatic actuation cylinders" on both sides of the mouth so it would close.
I love what you did with the eyes and the terrible black paint. I think I will do the same. The endo skull is by no means accurate (not Arnie's teeth, missing the square divit on the upper left side of the skull, wrong nose), but I got mine for cheap off ebay, and it seems easier to turn into a rod and wire actuated puppet than any of the other versions available (especially the resin ones from China). I'm also going to replace the crappy plastic "hoses" with stainless steel brake lines, and fix the nose as well (I really like what you did there).
Glad to see someone else has taken it upon themselves to fix one. They are a decent piece, but are by no means "studio accurate".
Strong Work!!!