There was one posted a few years ago on tformers. Its a homage to of all things, the Marvel G2 comic Edit- Found it for you http://tformers.com/article.php?sid=2070
It was a page from The Generation 2 comic, issue 12. Prime gets half is facemask broken off during a fight with Jhiaxus and you can see the "teeth" and some wires
Off topic, but I love scenes like that. It's always cool when a "masked" character gets part of their "mask" blown away, in my book. Never knew it happened to Prime outside of Galaxy Force. Pretty cool. I'm impressed!