Is My Regulator Working?

you see, my educated guess would be
last summer you messed up the reg settings so it worked when you had half cylinder full or so, then when you refilled lately you realized it is not regulating, must have got lucky the second time.

have you got a regtester or manometer when you said took it apart and out it back together, sounds like a breeze. in reality it is hard work to get it right. 

people do it all the time they think they can change few o rings, it does not work like that.