So after you blow the LP gauge on the Matheson regulator, you dunk the replacement regulator in water to find the leak.
You know there a chance that the leak was somewhere else and by dunking the regulator in water, you just created a bigger leak. Because you know, freezing Co2 gas and water isn't like combing chocolate and ice cream.
If that sellers refunds you, you put "A++++ EBAY seller!!!! BEST EVER" on the feedback.
I removed the pressure relief valve and replaced with a plug. Still no go. Then I replaced the LPG with one from the Matheson dud and still leaking. So in desperation I dunked the regulator handle and front half of the regulator in water and found the leak. It's between the front half of the regulator and the main body. I'll see if the seller will refund this one.