The washers need to be on the needle to keep it from moving back and forth in the slide. The normal position would be for the washers to be in top of the needle as a baseline position. If you then want to richen the needle you would put one washer on the bottom between the needle and the slide but you still have to put the other two on top, and so on, and it will progressively make the needle richer until you have them all on bottom.