Remington 870 - Trouble Loading 6th Shell in Tube

[Captains1911]

This is a brand new 870 Express Synthetic with a factory 2 round mag extension. When loading 2 3/4" shells, often the final (6th) shell will not load, because the entire 5 round stack is "stuck", meaning I can't push them into the tube any further, as if something is catching or binding. After taking it apart and studying it closely, I'm almost positive that the forward end of the follower is catching on the joint between the mag tube and the extension tube, as if the two don't fit together exactly perfect and therefore create a lip for the follower to snag on. The instructions that came with the mag extension indicate not to over tighten the extension tube, which I am not, but I don't think that matters.

Is this a common problem? I was considering upgrading the follower and spring to this:
http://shopwilsoncombat.com/Spring-F...info/SGSFK-EX/

Will this likely solve the problem, or is there a better solution?