Theoben MFR Action Valve 'O' Ring Applicator Tool Complete With 5 Spare 'O' Rings.
The simple kit that you have really been waiting for!
Now you can undertake this task yourself, with relative ease, and not get charged a small fortune.
The fitting procedure is as follows after removing the old O ring:
1. Place one of the new O rings on the end of the probe in the action block. It will sit there quite nicely.
2. Push down onto the O ring with the applicator tool, and this will push the O ring over the spigot and locate it in the correct position.
3. Apply a small amount of silicone lube to the O ring with a cotton bud.