yes it does need cleaning, un bolt the four bolts ,careful not to drop the washers or the bolts so use a magnetic pick up, lift off the tower , you will then be able to pull it apart , clean it up with engine degreaser or diesel , make sure it all nice and clean and dry .Refit ,using the old seal unless its furbarred (trip to gsf or vw if it is) , refit the bolts and washers (8 nm if its suits ya) .
one thing to look at while the tower is off is if there is any oilly/carbon build up in the hole , if so carefully clean it off using hoover and a screwdriver , cos you dont want any crap fallin drop the hole.