Hi!

You have a busted diaphragm in your regulator and the propane is leaking out
the little vent hole on the top side.  They're non-repairable.  You may be
able to find a suitable replacement at a local RV dealer or the local major
propane supplier/dealer.  Otherwise back to mail order or to your local VW
dealer.  ($$$!!! - -Argh!)

In the meantime DON'T try to operate your propane system!!

good luck

leonard jones