You don't have to take the magazine tube off to install the new spring and follower. Just unscrew the end cap.
It's your shotgun. Do what you want. Please don't doink with unscrewing the mag tube. If you remove the mag. tube cap you will find a little cup that keeps the spring from flying out. Carefully finesse that out by prying, and remove the spring and follower. Assemble in reverse order, and swab out the tube first because it is filthy. I would reinstall the spring keeper. This is the recommended procedure. It's your gun.