Clack valve - Refill port plug leaks

[electrotuko]

Clack WS1EE used on a iron removal filter/tank, Backwash only valve.

After a month after an installation it started leaking from a Refill Port Plug.
The water drips (1 drop/hour) from the locking clip holes.
I removed the plug, visually inspected, all looks good, O-ring looks good, clean.
Lubricated with silicon, re-seated. Still drips.
Removed plug again, removed O-ring, wrapped few turns of Teflon tape on the plugs neck, to make O-ring sitting higher, making more tight contact O-ring – Valve body.
Still the same.
What can be a root cause?

 

[ditttohead]

Can you post a picture of the leak? Do not add teflon in an attempt to fix an o-ring leak.

 

[Sponsor]

 

[electrotuko]

Posting image of the leak place.

 

[electrotuko]

When Clack is in a service-"home" mode there is a full water pressure under that refill cup.
Not sure if this is normal. I have inspected a spacer stack assembly, it all looks good.
Replaced refill port plug with new and new O-ring (no teflon), same issue.
One thing I noticed that, since it is a backwash only filter configuration, there is no Regenerant piston installed.

 

[ditttohead]

That portion will be pressurized, it should not leak. If you replaced the cap and o-ring and the problem persists, then you have a flaw in the valve body.