You can use a manometer and check the pressure with something using LP.
I have seen a couple of Airstreams that have somehow ended up with water in the LP lines. We blew the lines out and the problem was solved.
If that regulator is not working properly, it would be a very good idea to simply get a new replacement. Replacement regulators are inexpensive, mushroom clouds and smoking craters, not so much.
Meddle not in the affairs of dragons, for you are crunchy, and taste good with ketchup.