I have a six station A&A Manufacturing pop-up cleaning system and some of the pop-up heads are not rotating. The filter has been flushed and the water pressure is good in the system. I replaced all the T-valves in the actuator and rebuild / replaced the gears. Some of the heads on the same circuit rotate and others do not. I took out the heads that weren't rotating and allowed the system to flush out any debris in the lines. I then cleaned the heads and lubed the orings of each head and tested the spring mechanism by pushing on the bottom. They all rotate manually when I push up on the spring. I reinstalled them and they still don't rotate. I even put them in a different location and they still don't rotate. Is there any other type of maintenance or repair for these heads that I'm missing?