changing the ejector is not simple. It takes a couple speical tools and requires the receiver to be refinished. My one gripe with the 870 design. If they had drilled and tapped screws instead of rivets it would be a simple fix. Make sure the gun smith who does this also refinishes as the rivets will not fit flush once replaced and have to be ground flush. So, it is best to make this a factory repair as they are the only ones who can apply that finish on an Express model. Or, find a place to parkerize it.
As for that Tactical Rem Joke tube breaking. That was the best thing that could have happend to you as now you can simply screw in an I/C or Mod tube and your good to go.
JD McGuire, Owner
Remington Law Enforcement Armorer
Mossberg LE Armorer
If you're going to a gun fight, take a shotgun. If you can't take a shotgun, don't go.