What is your watering program? How often and for how long do you water?

How would you characterize your soil? Sandy? Clayey? Something else? Hard? Soft? Can you stick a screw driver into it easily? How far? Try that in several places.

I water by sprinkler as needed, typically once a week in the summer and try to water deep. I aerate once a year in the fall. A screwdriver can be inserted pretty easily outside of mid summer and I've waited too long to water. This time of year I can put one of those big yellow tent stakes in by hand a few inches.

6inches deep by hand without effort? If you have efoort with the screw driver might be different problem.

I would try a 6 inch screwdriver in the area without growth. I have a few similar problem spots. The grass is stunted and weeds compete. I believe I have larger rocks underneath and will try digging in the spot mid August before reseed.

I didn't say 6 inches or easy :) -I like your rock idea, the house is 4 yrs old and I often find a large rock under dandelions. I'll dig a spot or two up tomorrow.