Third PPR o-ring

[Bitsyncmaster]

Looking closely at my primary pressure regulator I see there is a third o-ring (inside the "nut cap"). It looks like you would need to remove a C clip on the needle side and then remove the cap on the nut side to replace that o-ring. I've never done that o-ring replacement. Have any of you replace that o-ring yet?

[Bitsyncmaster]

I checked if I could take that end cap off (4mm allen cap) and it won't come off. I would think you would have to use heat to get it removed but that would damage that O-ring and maybe the spring so I decided not to chance it.

[Ron]

A little late, but you can see how it is assembled here:
https://dmctalk.org/showthread.php?18638-Finding-cause-of-loss-of-rest-pressure&p=262272&viewfull=1#post262272