Ok everyone have a good new year laugh!!
Changed the filters and lost half my pressure in the system.
Burnt out a booster pump trying to fix it.
New pump still 40 instead of 80psi.
So today got fed up and stripped the lot down, checked all connections, new filters, silicone grease on o rings and new resin. flushed the filters to drain for half an hour.
Ran for a couple of hours without the booster.
Switch on booster pump..... guess what 120psi!
probably down to new filters.
Tell you what though its producing like rabbits!
Apparently the 350GPD systems have this problem quite a lot.