A few years ago we installed a small 3 zone spray head system to do a about 1000 sq feet of raised landscape beds. The homeowners apparently got tired of that landscaper and had a local hotshot guy (20 years old, thinks he owns the world) come in. He put a nice water feature in it, and tore our system to pieces (even in area's that he shouldn't have had to touch.) Anyways, I spent the last two days doing a complete reinstall, this time with 300 series Stream Rotors as per his request. The only thing I didn't replace was a the mainline to the manifold, though I moved the valves over about 15 feet. He had broken the mainline a couple times, and repaired it already when I had got there. In the back of my head I though about flushing out the line, but I didn't do it. So, after I have 4 valve installed in a valve box, and I pressurize the main, all 4 stick open. Hurray! DVF-100's take a while to take apart when your in a cramped box, and each one had a few rocks stuck under the diaphragm. This guy is going to see a nice bill.