Harvey, go ahead and respond here on this post.
This came via email:
Mr. Fixit, Thanks for your reply. The line is a drip line + mini spray heads. The line does not have a filter, The 5/8" black tubing is properly attached to the 3/4" PVC to the valve and I've check the line for leaks and could not find any. harveye3
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Harvey I'd venture to say that not having a filter is a problem. Those sprays can easily become clogged. You may need to clean or replace all of them. Lots of times when a head isn't working it's the fitting where it connects into the 5/8 tube.
Try this when you think the valve has shut down. Go to the end of the line and open it up. See if the water doesn't come gushing out.