Main drain had debris inside under the cover. Removed cover and say nothing other than small particles of dirt, leaves etc. My pump has two inlets one from the skimmer and one from the vacuum port. Therefore I do not know how the MD is plumbed into the system. I can turn the valve completely to open for the skimmer and it works fine. I can turn the valve to the vacuum port side and as long as I have the port open it works fine. NO Suction comes from the MD and it appears the pipe to it is smaller than the others because when I tried to put a garden hose in it barley fit. How do I unplug the MD. Any ideas will help, Thank You