If you are servicing a ST-10/15 tail-stock built from approximately August 2015 to August 2018 and the connecting quill has failed, then you will need to order service kit 93-2891. Use the kit to replace the washers (1), the O-ring/ (2), and the quill (3).
If you notice the connector quill did not fail, but the washers did, then only order the washers and the O-ring. Part numbers: 45-0178 x2 EA and 57-2126 x1 EA. This is only for assemblies built with connector quill 20-6790.
To identify the connector quill used from August 2015 to August 2018 see the bore on the quill to the left (4). This is part number 20-6790. The quill on the right with the chamfer (5) is part number 20-6790A and will be in production August 2018 and after.