Brass Champion/Superior Sprinkler Controller/Actuator Slow Drip

I've replaced all the rubber parts on my sprinkler controller (see the diagram of similar unit), but it still continues to have a very slow drip (inside the line). There's no visible water on the outside of the controller, but if I remove the anti-siphon cap I can see a slow drip. The unit

800 - Superior

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Brass Champion/Superior Sprinkler Controller/Actuator Slow Drip

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