Thanks for your help. I will try that. Unfortunately, I'm not too familiar with the anatomy of the sprinkler head. Am I taking the "guts" of the sprinkler out? Do I need to worry about any springs popping out or anything? You are right, some of the heads have sunk down a tad below ground level so hopefully this will work. The water pressure is fine, no changes. Worst case scenario would buying new ones help? Can I just purchase the "guts"?