Well guys, today I was able to fire the 870 super mag express to check the repair. It performed flawlessly. I shot about 40 rounds and all extracted very nicely. Soooo, it appears that if you are having the same problem an extensive chamber polishing appears to be the fix.
BTW, Remington promised me to reimburse me for the shipping charges to return the shotgun. I sent in the required paperwork over a month ago and have not heard a word. I guess actions speak louder than words.