Help needed, tank/valve issues

[MattBPW]

Hi folks, hoping I'm just being a bit thick here but I have a question.
I recently purchased a Catalina S40 for use as a slung pony bottle.
First stamped in 2013 and then left in a LDS till they closed down recently. So I picked it up as being in "As new" condition, never dived and to be fair it does look brand spanking new.
Anyway, I get it, the shop does a test, re-stamps it for me, fills it and I'm out the door a happy man.
BUT when I get home I connect me current and confirmed as working reg set (Hog D3 first stage) and I'm getting audible air hiss.
It's a yoke valve with DIN insert so I'm just wondering what people think could be the cause?
I've not yet tried replacing O rings.
Thanks in advance.

 

[johndiver999]

Remove the din insert. Replace that internal din o ring. Reassemble

 

[runsongas]

make sure to check the donut insert is tightened all the way too

 

[Jonny Wishbone]

All that others stated and/or connect another reg to rule out your reg...

 

[rhwestfall]

I'd replace both o-rings (internal and external)

 

[MattBPW]

Many thanks folks, don't currently have a second set of regs to test the tank with but I have tried my regs on another tank so I've ruled those out in a reverse kind of way.
I made sure the insert was fully nipped up so it wasn't that.
So now I've pulled the insert and will be changing both rings and hopefully that'll do it.

 

[tbone1004]

if it doesn't, then it's an o-ring inside the valve knob assembly that can be changed pretty easily without draining the tank.

 

[Jonny Wishbone]

I hate to say this but i have seen some Dive Shop Techs that are dumb as rocks and take a big wrench and put it right across the face of the yoke portion of the valve to remove and replace it. I still have one that shows the mashed up metal but its not a convertable valve like yours. Hopefully its not the case here...

 

[MattBPW]

On the way back home now, as hoped, they pulled both O rings from the din insert for me and replaced them free of charge. The inner one was fairly flat and the outer pretty cracked.
Feeling confident.

 

[MattBPW]

Done, fixed, confirmed after replacing the rings free of charge she's back in diving order. Thanks for the advice folks, much appreciated.