To clean the PS screen, what I do is get the bottle out of the mount and tip it so you can remove the return hose. Place that hose into a bottle (2l work good) and start he van and go from lock to lock to pump out all the fluid. I then remove the bottle completely and back flush the screen with a solvent. Can be a spray can or you can just use gasoline. Let the bottle dry thoroughly and blow out with air if needed. Remount the bottle and fill with new fluid. Start the van and turn from lock to lock again. You will need to add more fluid. Turn from lock to lock with the reservoir at the proper level until you get all of the air out of the system. Result is new fluid in bottle with a cleaned screen. Some folks will put fresh fluid into the bottle in the initial step to flush the system before completely emptying it. If you do this, you are typically good to go for 50K+ miles or more.