On Wednesday, June 22, 2016 at 10:56:48 AM UTC-4, Percival P. Cassidy wrote:
Our sprinkler system has many daisy-chained sprinklers -- not the way to
do it, I understand, but that's the way they were.

A week or two ago I managed to chew up a sprinkler with the mower, and
when I unscrewed the damaged sprinkler dirt and stones fell into the
Tee. I cleared away all I could reach, then turned on the water to blow
out the rest. Unfortunately, it seems as though some continued straight
on -- toward the next sprinkler -- instead of blowing out from the one I
was working on. Now there is barely a trickle from that next sprinkler.

What would be the best way to clear the line? It's 3/4-in poly pipe.
I've thought of unscrewing that next sprinkler and trying to push stiff
wire back along the pipe, but is there a better way?

And is there a good way to prevent the problem in future? How does one
stop dirt and stones falling into the open line?

Perce

I'd try removing the offending head, then turn the water on briefly.
The heads typically have a screen at the entrance, that could be the
problem too. Some heads, eg rotor type, you can unscrew the head
from the shell, remove it, without removing the shell from the ground.
That can help avoid getting new dirt in there. It's always a problem
when you have a hole and are working on the pipes and wind up with
water filling the hole.