Hopefully this will be my last question for a while.
When adjusting the center width, it's very hard to notice the difference but maybe it's just me. The main problem is when I set the adjustment to 7, my center channel does not shut off. Why is this?

I assume you are listening to two-channel sources (analog, PCM stereo, or Dolby 2.0 sources) and applying Pro Logic II decoding when testing the center width adjustment, because it only affects Pro Logic II. In fact, I believe that those adjustments are only applied to Pro Logic II-Music (not Pro Logic II-Movie).

If you are using Pro Logic II-Music decoding with a two-channel source, adjusting the center width will vary how much signal stays in the center - and it should do so to a noticeable degree. While the 990 manual says that step 7 will basically shut down the center, I'm not certain if it really will. There was a lengthy discussion of that a while back, and I don't recall what we concluded at the end of it.

Now I feel dumb.
No I was not listening to 2 channel.
That was my problem.

I believe everything is set up now. I'll go enjoy it.

Thanks Gonk

Don't sweat it - you're hardly the first to get lost in Pro Logic II settings.