O-ring Seal for By Pass ( sold individually ).
Used in newer style By Pass used for Autotrol 255 and 263 / 268 Performa valves ( called the 256 for the 255 valve version, or 1265 By Pass for the Performa ( 263 / 268 ) ).
* The Repair is very simple, and logical.
* Turn incoming WATER OFF.
Open a faucet to relieve pressure still in pipes.
You remove the metal clips at the bottom.
With clips removed you will push up to remove each control knob.
Each handle portion comes up.
The rubber square and o-rings will be seen.
Lubricate the new rubber parts, o-rings and slide back together.
Put the new metal clips in place.
Turn water back on.
Test by pass for leaks ( turn each one on and off again ).
You will need to use silicone to properly lubricant the new o-rings when re-assembling.