Bent Supply Tubes

• If the sprinklers are running, there is a small supply tube that pops up above the ground. If this tube gets bent or broken, the sprinkler will become stuck on the outside or inside of the sprinkler body. Sometimes, you can gently bend a supply tube back into place. But if the connection is cracked or broken off, you will have to replace the entire sprinkler assembly.
  
  

Dirt and Debris

• Dirt and other small debris, such as sand, can become stuck in the small gap between the inside of the sprinkler body and the sprinkler supply nozzle. When the spray moves up and down, this debris can cause gashes and scratches over time. These gashes can lead to friction between the supply tube and the sprinkler body, causing the sprinkler to fail to pop up. When this happens, the entire unit must be replaced.
  
  

Crushed Nozzles

• One of the fastest ways to break a sprinkler is to run it over with a car or lawn mower. This will often crush the nozzle on top of the sprinkler. When this happens, the water will no longer spray correctly and the nozzle can become stuck in the body of the sprinkler. A crushed nozzle must be replaced. Depending on how badly the body is damaged, the entire unit may also have to be replaced.
  
  

Leaking Supply Pipe

• Most sprinklers rely on water pressure to push the nozzle up above the ground. When your sprinkler lines have a crack or leak in them, it's possible that the system no longer has sufficient pressure to push the nozzles up. You can test whether you have a leak by leaving the sprinklers on for 30 minutes, and checking the ground for signs of pooled water. The pool will likely indicate a leak underground.