WS1RB
The main piston and seal/spacer take most of the wear and tear in the Clack WS1 control valve. Eventually these components wear out, and need replacing. If your softener is constantly running to drain, or you're ending up with salt water in your lines after a regeneration, you may need to replace these components. It's highly recommended that you also purchase the Clack Service Wrench which makes the replacement of these components much easier.