Thank you very much for the information! However, that is for cleaning the *piston* with the sintered-metal insert. Those are pretty much acknowledged as being completely uncleanable.
I'm asking about the laser-drilled insert that goes into the body. This was a mid-1990's improvement in the design with a late-1990's improvement to the laser-drilled insert. Here's a quote from the SRB5300 Assembly and Maintenance Guide:
The problem is, I tried cleaning the insert in an ultrasonic cleaner, and of 6 of them, zero improved. So I must be missing something. Hence my question.
I know I can replace them. But I'd rather learn how to clean them -- I have a *lot* of Sherwood regulators...
The tiny laser drilled hole is open, or it's not. You made the comment in an earlier post: "no air bleed". If you can see a tiny speck of light thru the hole, there MUST be air bleed, or there's a separate problem going on.
Now if the bleed is present, but below specification, that is a function of the hole diameter and/or the effectiveness of your U/S and solution.
If there's zero bleed, but you can see light thru the hole, there must be an obstruction in the pathway to the little rubber bleed plug.
If there's light visible, I'd switch from vinegar to phosphoric acid. You can get food grade phosphoric acid on Amazon. Start at 3% and then double it. Add a few drops of Dawn and a few drops of antifreeze to help penetration. Warm it.
Let us know!