I think the filter your talking about is the one in the cap/filler neck? its there so you don't pour crap into your powersteering when refilling it, as most people use new fluid when they refill the system it never really gets dirty, if yours is then its only a stainless steel filter so take it out and crank some brakleen or similar through it let it dry and put her back in, but personally I wouldn't bother unless you really have some spare time to do it, but on the other hand it would only take 5 mins.
