Oops, sorry I missed this. The forum software is set to mark forums as 'read' when one logs off. I get on for only a couple minutes at times and of course when I get out everything now looks like I read it. Enough of that. If anyone doesn;t get a timely reply simply add another post to bump it to the top of the list. Posters do this all the time.
OK, on to the problem. My next logical question is what does the pressure look like on Backwash and Waste? Waste simply dumps the output of the pump to the waste or discharge line. You've got to try and isolate where the restriction lies. Sure sounds like something in the return piping. Also try taking the eyeballs out and see if the pressure drops. On my pool I bored out the eyeballs to the largest diameter I could just to cut the restrictions.
Al