I have a Hayward SP0410X502S Micro-Clear Slide Valve Assembly. I got this to replace a worn out one when I installed a Solar pool pump system about a few months ago. Now when I try to backwash the DE filter it sucks the valve back down into the normal opperation position. Heres a link of my valve assembly doing it.
When I pull the valve stem up and put it in the locked position there is no water movement in the pump basket while it is on. Any one have any advice on what might be going wrong?