As goodolddays pointed out well worth doing on all machines as its amazing the crap people spray squash or squeze on these to try get them going (BLOODY DRONGOS SOME PEOPLE)

Step 6  Remove the wiper plate or fingers whichver you have this is usually done by either removing the screws or a nut holding the wiper in place.  When taking these apart i set them beside the unit as i remove them so i know where they all should go