Your descriptions equal love-care-attention to the bike. This tensioner is the weakest part of our CX/GL line, although there are so many CX/GL's around 30+ years later because they run like a Timex. It is wise for you to ask this Forum for guidance on the Tensioner.
I might be wrong, but I think you have a winter project on your hands, after this 2011 riding season. For some reason, and it could be chain wear, the gap position is way over 50% in the heavily worn category.
Replacement Chain and Tensioner can still be had new from Honda, if needed. If you don't have a manual, get one. Clymer part# M335 would be my recommendation if not downloaded first. And continue to involve us on the Forum. We are rich source of support. And someone local to you could surprise you and make a field trip to your house during the repair. Just ask, although I'm 2,500 miles west.
Most engines, including our old CX/GL's are dull black inside from the oil/shellac and smoke deposition, making them dark and gunky. Your engine is not at all that way. I would guess that your seat and bike rubber parts are all in good condition too, just like the inside of your engine?
And you should hear several of us Forum members stating the exact same thing.