Pim,
With the inner primary cover already in place, you might be made crazy by trying to get your washer stack in place between the frame and the tab on the primary cover. What I did was to measure, with my caliper depth gauge, approximatly how thick the stack must be. Then, I took some cyanoacrylate (super-glue) and glued the stack together so that it could be inserted from behind in one piece. It took a couple of tries to get the right stack height, but if you just use only a tiny amount of glue, washers can be separated from the stack easily enough to make the adjustment.
Richard L.