Pertains to the 19°,26°,36° and 50° Lens Tubes:
In 1996, ETC was using for the S4 Lens Tube:
4x HW391 --- Screw, 8-32 x 3/4 phPHMS B/Z
8x 7060A4012 --- Lens Pad Support
6x 7060A4009 --- Bushing Guides
Around 1997, ETC started using for the S4 Lens Tube:
4x HW369 --- Screw, 8-32 x 5/8 PhPHMS BO
10x 7060A4012 --- Lens Pad Support
8x 7060A4009 --- Bushing Guides
Around 2006, ETC started using for the S4 Lens Tube:
4x HW3154 --- Screw, 8-32 x 5/8 PhPHMS BO Taptit B/Z Waxed
10x 7060A4012 --- Lens Pad Support
8x 7060A4009 --- Bushing Guides
The HW369 is a machine screw and required a nut for assembly.
The HW3154 is a thread forming screw that threads into the casting so no nut is needed. If the S4 had the HW369 screw + nut, then those need to be used for replacing, because the screw hole in the tube would be too large for the current HW3154 screw.