callinectes

While getting out my Nova recently I noticed that the spring in the magazine tube was stiff and was having a hard time loading the magazine. After I removed the plug and spring I found some rust pitting that was causing the spring to hang up. I cleaned the tube really well with brush and pads and I have been unable to remove all the rust from the pits. The spring still gets a little hung up in them. How hard is it to replace the magazine tube? I do not think the tube is that expensive and it is probably cheaper than sending the gun to Benelli for warranty work. Thanks.