Counter Pressure Bottle Filler Missing a part???

[OldGilbert]

I have been using the More Beer counter pressure bottle filler to bottle beer for a while now, but I went to use it yesterday and the CO2 just started coming out put the pressure release valve with no resistance. I tightened the end cap as much as I could, but found there must be a missing part. I have the spring and the screw on end cap. Does anyone know:

What this part is that I'm missing and what it looks like?

Can I get get a straight replacement if I can not find it?

Thanks for any advice you can offer

 

[microbusbrewery]

Here's a pic of the disassembled valve. I'm guessing you're missing the little piston piece with the o-ring. I'd call morebeer and see if they have any spares. Worst case you can buy a new valve, https://www.morebeer.com/products/stainless-gas-pressure-relief.html