We moved into this house with sprinkler system in place last July. The sprinklers all worked great until the end of last summer when we noticed the first zone seemed to lose a lot of pressure. All of the other zones work great. I don't see any wet spots like there is a break in the line. We had a broken head on another line with water shooting straight up and the rest of the sprinklers in that zone still had good water pressure, so I think it takes a lot to lose pressure. I removed the solonoid (sp?) and ran the zone manually, but still had poor pressure. Any ideas?