I had that problem when I put on my MPS. Turns out the bolt is supposed to have some thread sealant on it like teflon tape. I had bought a new on and when I went to put it in I realized the old one had this stuff on it.

Other than that, as reptile mentioned, the only thing I can think of at the moment would be the snout seal. The nose drive is not a complicated set up and there isnt much that can go wrong with them.