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That doesn't look bad enough to warrant replacement, for sure. Just keep a eye on it, ad it it continues further, come back ad ask again. For now, get the feeler gauges out, and measure the dip(straight edge, feeler gauge), ad record it. Check again in 6 months, then a year, etc... It should stop at some point(wood can only move so much before it takes its set). Only if it doesn't ever stop moving should yo interfere.

[QUOTE=rich altieri]The soundboard in the area most effected seems very thin.
It is definately Englewood so it might be too thin for Englewood.
I might try putting a Spruce path in the area[/QUOTE]

The top looks thin around the soundhole in the pics, but it might be an optical illusion. Did you measure it with calipers? It would be interesting to see if it's still at .100" or much thinner.
It's hard to generalize about species, but when I worked in a production shop, Englemann tops were routinely at least 20% thicker than Adi tops. They're softer and do sand much faster…
I am not sure a spruce patch would help anything. Wait and see how far it goes.

_________________
Laurent Brondel
West Paris, Maine - USA
http://www.laurentbrondel.com/

First of all, Mario's comments re. measurements should be taken very seriously.   There's all this talk about what kind of spruce and no talk about that particular piece of wood. How stiff was it to begin with?   

Secondly, what you see in the stress and beginning implosion there is exactly what flying buttresses counteract.   If you're depending on the top to hold the guitar together, it needs to be stronger in the upper bout than this guitar appears to be.   But there are other ways to support the neck and fingerboard torque...

What Rick and Mario said.

For the past couple of years I've been measuring the Young's modulus, a measure of the potential stiffness, of all of the tops I get in. You would be amazed at the range of variation within a species. I have Englemann tops with a lengthwise Young's modulus as low as 8000MegaPascals, and as high as 16,000. The low end is right down there with the least stiff Western Red Cedar, and the high end is like Red or Sitka spruce. At a given thickness, the low end top would be half as stiff as the one on the high end. This is _not_ a judgement about the 'grade' of those tops: both of them look fine and have decent cross grain stiffness, one is just a lot denser and stiffer than the other.

That's the widest range of variation I've seen in a single species, but it's not all that much wider than most of the others. It does no good at all to arrive at the thickness on the basis of species. You've got to measure the wood somehow. Deflection or vibration tests are the most accurate, but even educated thumbs can work for some people with enough training. If you're just starting out, and don't have a more experienced person to help you learn about this, by all means try one of the objective methods; deflection or vibration testing. They are not hard to do, and then you'll _know_ what you 've got, instead of guessing and hoping.