I just started having low water pressure while softener is in use. My unit is about 9 years old, Ive never had a problem until now.I tried the usual things, cleaning the nozzle and venturi, I replaced the gasket,cleaned the small wire screens in venturi housing and in the brine valve assembly,tried water softener cleaner also. The water pressure remains low.When bypassed its very good pressure.I noticed now when its in the brine cycle it really doesnt suck it into the filter,thus producing lots of leftover water in the tank.what else is there to check to solve these problems.