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"?
A few I-20's in each zone fail to pop up this season. I've had the system for 4 years now and a few zones did it last year and now every zone (7) have one or two that won't pop up. Nothing has changed. I literally have to go around and pull up on them to get them up and going. This makes 3am waterings a little difficult and I have dry patches to show for this shortcoming. Do I-20's go bad? Do these need replaced? Any help you can provide would be helpful. Thanks!