Propane tank two stage regulator "excess flow valve"

[thewrongway]

We have a very small amount of propane "flow" from our door side propane tank (yes, it is full). I have checked both regulators and confirmed the 30# output. When swapped to the door side tank there is no or possibly very slight flow. By removing the "excess flow valve" 30# is at the end of the hose. This "valve" appears to be a brass M x F adapter with a rubber disc that is spring loaded as in a "check valve". Anyone had this issue? I am trying to reach Grand design PARTS at present.
Thanks

[gbkims]

I dug up a bit of info on this valve that has been mentioned a couple of times, learned a bit more as well.
I didn't find the fitting part number.
It appears like the check valve is pre-installed on the Fairview auto changeover that they sell.
GR-9994 Tech Specs https://www.fairviewfittings.com/Use...GR-9994%29.pdf
"INVERTED FLARE INLET CONNECTIONS WITH BACK CHECK VALVE"
https://www.amazon.com/Fairview-Prop.../dp/B071D1SYLY

https://www.mygrandrv.com/forum/show...l=1#post201182
https://www.mygrandrv.com/forum/show...-System-Issues
https://www.mygrandrv.com/forum/show...ll=1#post47250
https://www.mygrandrv.com/forum/show...ll=1#post47269
https://www.mygrandrv.com/forum/show...ll=1#post54485

https://www.rv.net/forum/index.cfm/f.../tid/25482343/
"The check valve appears to be regular flare fitting with a plastic insert, spring and plastic shut off piece."

Fairview Fittings: Auto Changeover Regulator
https://www.fairviewfittings.com/Ind...egulators.html

Marshall Excelsior - High Pressure Regulator
https://www.marshallexcelsior.com/si...%20Catalog.pdf

The ABCs of LPG: Understanding LP-Gas and Propane Systems in RVs http://www.trailerlife.com/tech/diy/the-abcs-of-lpg/

[WhittleBurner]

Something to keep in mind is your propane system has an emergency shut off in case of a leak. When you open your propane bottles open them slowly so as not to have that shut off valve not shut down your propane flow.