For those who prefer the "bare" shaft look, these dust washers fit the circumference of the Sanwa Denshi JLF joystick series without the use of the shaft cover.  These come in a set of two, where one can be used in between the joystick and control panel (inside), while the other on top of the control panel (outside)

Image shown of dust washer with Sanwa Denshi JLF joystick (which is not included)