J,
Before trying to do something with the kit, have ya tried using some gunscrubber or brakecleaner to douche out the bolt assembly? You may have something in there stopping the pin from going forwards all the way.
Another thing to do, would be to call Mossberg. I've seen them warranty guns that were on their second or third owner. I think the original warranty on them runs for either 10 or 15 years, but I may be wrong too.
For me, if I doubt something up front then it'd be better for me to let an expert do it or at least have one close to hand.
HWD