let me start by saying I rarely use PGPs but use them on low flow systems because of the small nozzles. So we did an install and installed many of the heads with the smallest nozzles due to the well drawing down. This job was finished 2 weeks ago and have been back 3 times for heads not rotating. We have changed out 6-7 already. I have noticed with the tiny nozzles the heads turn very slowly to begin with. Do you think there is any correlation or just bad batch of heads?