Right between the gearbox and drag there is a lot of back and forth play causing the reel to not be smooth. What should I do?

Are you referring to back play in the handle or some in and out movement of the main shaft? Both are normal tolerance issues and vary from reel to reel. Either can be addressed but maybe not eliminated. You can either fish it as is with no ill affect or send it in for professional service. If you send it here, be sure to include your screen name to receive a 10% discount.

DVT is right. I've yet to see any reels that don't have at least a little play in them, though some more than others.

My revos have a bit of play in the main shaft that's felt in the handle. Load them up by dragging a lure through water, or better yet, a fish, and that play goes away.