My bet is that the poppet is either the wrong type for the post, or it's a "universal" poppet that hasn't been trimmed to the correct length for the post.
All poppets come out. Try prying the feet of the poppet in from the underside of the post to remove it. A small pick or small screwdriver works well. Once it's off you can compare it to the poppet type that's supposed to fit your keg.
I'm trying to find some porn filmed by a dog wearing a GoPro. - SharonaZamboni
Hunter, when you get bored, will you put a taco in my elephant's hands for me? - Hat