I have a ??? about my regulator on my LP tank... I went hunting deer last week at our camp, I turned the furnace on and proceeded to un-pack the truck.. On the 500 gal. tank, the reg. made a kinda a funny noise,, like a loud purrrring... I tapped the reg. and it quit.. My curiosity got the best of me and I unscrewed the black plastic cap on the reg. That's where I think the noise is coming from.. I wanted to put a drop of oil on the rod and spring in there,but it was cold and thought ,maybe not a good idea.. Should I call a heating contractor and have the Reg replaced or is it something simple.???