SPRINKLER TALK FORUM - You Got Questions, We've Got Answers

I started up my system this spring and had a leak from the cover of the back flow assembly. It is a Watts 009m3-rc3 3/4" backflow device. I purchased an o-ring repair kit, replaced the o-ring, and now I have water exiting the top of the cover through a tiny little relief that has a tiny copper plug in it. I don't know what I did wrong or if there is just something wrong with this little pin that goes in the hole. It doesn't look like it had a washer there and it looks like it always has had a gap for overpressure relief. It is not the port that you can hook air up to or testing equipment. The pin is very small and can be removed with a screw driver. I am thinking that this is not my problem, that I need a new diaphragm and it is just functioning the way it was designed. I can't take a picture small enough to attach here. Sorry.
Thanks - John

Quoted from "Wet_Boots"

go strictly by the factory manual on these things

Seriously, anything helpful would be appreciated. I obviously went by the manual, that is how I purchased the kit. The Manual is not helpful in this case.

Quoted from "Wet_Boots"

There is often a need to apply some silicone grease to RPZ parts you are re-assembling, to get a perfect leak-free fit. This would especially be true for the relief valve section. Look for this in your manual.

Do you know if there is a piston o-ring on the top part of the plastic relief valve? If so, I think this is what went missing. I have only found it in one schematic and it is not in the manual.