Sprinkler valves not rotating:

1. Not enough water pressure>>Split zones up further and add a few more valves. You can test this by moving a working sprinkler to a non-working sprinklers spot and see if it also doesn't rotate in that spot. Then you will know that this particular spot is not getting enough pressure.

2. Debris in sprinkler head.>>Clean them out!

Otherwise, not much you can do besides replace.

Thanks for the reply. There's definitely enough water pressure. I can try cleaning them, though how to disassemble those things isn't obvious. I may be looking at replacing them...pity.

You may have to contact the company in order to find out how to clean properly.

Just did; got an email back. No procedure, no parts. You have to replace the entire thing.

Oh well, it was worth a try.