As Krona said, the key thing to get working is the adjuster plate. If it doesn't move with respect to the blade platform (where the blade goes), it won't adjust. You should be able to move it by pushing up from below, and you'll see the adjuster bars protrude up through holes in the blade platform. Most of the time, those bars are stuck to the blade platform right where they come through the holes due to soap scum, or corrosion. The hot water and soap should get it working again with time, and gently working the adjuster plate up and down.
As bob mentioned, dis-assembly is possible, but that should be a last resort. It's rarely necessary to do that.
James - 2011 R41 w/Weber Handle, Feather, Arko (face lather), TGN Super Silvertip brush, Gillette Sun-Up AS
BOTOC - LOSER - ARKO - TOFLAC-U - GNU - B.E.A.S.T