your bolt sail and inner back latch orings are big hitters for FSDO, as well as the third inner can, but try the bolt sail and back latch ones first. makes sure they are a snug fit, if possible get your hands on those green orings. As far as changing the inner can oring with out a oring pick, pretty much impossible. Just go pick one up for a few bucks.
If you're a Christian baller, put this in your sig
U.S. Army 92F