After 8 summers with little to no problems, this year's pool season is turning into quite a challenge. Thanks to SLAM, my water chemistry is perfect and thanks to feedback here, I have a new pressure gauge on my clean DE filter. After I removed the obstructions from my skimmer baskets, cleaned the filter again, replaced the gauge, and turned on the system, it was working perfectly. Then I started to see DE return to my pool again. When I went to inspect everything I noticed some water trickling out of the backwash pipe...not much, but a slight stream. I have also noticed water pooling around the backwash valve handle and it becoming tougher to turn. It looks like there are a few things I could potentially replace here based on reading other posts, but not sure which items apply to my specific backwash valve. I posted a picture...would it be O rings, spider gasket, diverter? I feel like I'm replacing so many things, not sure which are the right things and which I'm just tossing money at. 
Hopefully that work you did will hold you over for a while.