These valves are no longer available, so you'll have to find a used one.
But, you might be able to fix it.

First, remove the fridge door and the frame.  Then remove the metal
"Westfalia" front panel by first removing the knobs, indicator light plate,
and then the side and bottom edge screws that hold it in.   Pull down and
tip out the panel bottom edge to clear the stove shafts.  You'll see now
that the valves are easy to remove.  They are different right and left, and
keep track of the orientation of the flat on the shaft.  The shafts come out
by removing the retaining clip and nut.  I've not gone any deeper than that,
but if the valve itself is frozen, not the shaft in the nut, you can try
soaking it in vinegar overnight, but it may be a lost cause.

The early valves like yours are larger than the later ones ('85 on), so look
for one of those on the list or The Samba.   I found a right side valve
here.

Stuart, BTDT.

-----Original Message-----
From: Vanagon Mailing List [mailto:vanagon@gerry.vanagon.com] On Behalf Of
Timmy Evens
Sent: Tuesday, August 21, 2012 8:51 AM
To: vanagon@GERRY.VANAGON.COM
Subject: burner replacement

i've got an 83 with a stuck burner knob thingy. was working fine but now the
shaft that controls the burner is stuck off (better than on!) can anyone
point me to a tutorial for replacing these things? or where to even buy the
parts?

thanks
tim