NSK Ti-Max Z800L Manuel D'utilisation page 22

11. Replacing the Non-Retraction Valve
A water Non-Retraction Valve is integrated in the Coupling Joint, which shuts off the water retraction directly at the handpiece head to prevent fluids
infiltrating the water line. If water is beginning to leak from the handpiece, replace the non-retraction valve.
NSK Coupling (Z800L/Z800/Z900L/Z900)
1) Remove the Coupling Joint from the hose.
2) Remove the back-end Gasket.
3) Pull and remove the water tube, and replace the Non-Retraction Valve.
4) Insert the new Non-Retraction Valve securely and remount the back-end Gasket.
* Refer to Spare Parts List to identify the correct parts.
Back-end Gasket
Non-Retraction Valve
Fig. 20
21