If you need immediate gratification, take it to a shop for a professional setup for the weight strings you want to use, and include a new nut (Tusq or bone would be really cool). It could be something as simple as the neck being at a slightly wrong angle and needing a truss rod adjustment or a worn nut or bridge, all very minor. But while they're at it, have them look for internal damage.
Also, I don't like Martin strings. Never have. To me, they sound worn out and dull when you put them on. I like new, bright, sharp strings. It's a personal thing. If you aren't so worried about immediate gratification, just try some different strings on it. I'm a fan of D'Addorio strings and play around with the different kinds. Some pro friends of mine won't use anything but GHS. Still others like Ernie Ball. And of course, there's a fair number of people who like Martin. I'm just not one of them. For fingerpicking the D'Addorio silk and steel strings are good, but SO loud for strumming. I also like the Elixir nanoweb coated strings. They seem to last longer and hold their tone well. Play around with different weights too. I usually use .11's or .12s. In my opinion, .10s (aka ultra lights) sound weak and jangly on any acoustic. If you're going for jangly, then go with .10s. If you want a fuller sound, go with as heavy as you can get away with in your style. For me, that's usually .12s.
Granted B chord amnesty by King of the Mutants (Long live the king).
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