ERuhl

Sorry, I meant regulator filter screen. It's accessible by removing the pressure regulator on the back of the pump. There was a post on here recently (or TDR?) that was discussing weak power steering, and they had a link to pics of the disassembled regulator and the filter screen. Switching to synthetic cured the cold temperature vibration for me, but others have mentioned cleaning that screen improved it as well. Hopefully someone else will have a link to the pictures so this makes more sense.

Found it, but you have to be a TDR member to read it. Perhaps a resident TDR member can share the info.