I have a Mossberg 835 that has the factory Modified tube stuck in it. It has only been in for two months. I took out an after market x-tra full before I put the Modified in. The shotgun is 14 years old and I have changed the chokes a countless number of times without any trouble. I even let it soak in WD40 for 30 minutes and it still would not come loose. Any advice? I love the gun and don't want to do anything to damage the barrel so no extream suggestions please. If it won't come out it will just be a dove gun which is basically what it is now anyway. Thanks for any help.