Hello, I a little background on my issue. I live in Michigan. When we moved into our home ten years ago, the lawn looked terrible. For a few years I worked on it and it started looking great. The last few years it has looked terrible. We can reseed the spots and they just come back. I have dug about 1 foot deep into the spots, replaced with clean soil and reseeded, it still does not grow or the bare spot just moves. I aerate twice a year, in the spring and in the fall. Any ideas what is going on here? Thank you in advance.