Matt,
I don't know if your fridge is like my 3-way in a 1982 diesel westy, but
here's what I did.  I don't know that anyone else should do it, but it
worked for me (that's my disclaimer ... if you blow yourself up, don't
blame me).

I did take the fridge out to service the combustion chamber (last night,
actually).  The thing kept going out.  You will need to remove the flue
vent to get it out.  But, it is not as hard as you might think.  The only
thing I needed that I didn't have was a 20 or 21 mm wrench (I can't remember
which right now).  Anyway, after I took the thing out, I dismantled the
combustion chamber (about 6 screws) and carefully removed the rubber
gasket.  I then used brake cleaner to clean the vent tubes and the combustion
chamber and also the drain plug.  I also cleaned the gasket with this too.
I don't think you ought to use penetration oil to clean here.
Ok, I squished the rubber a few times and then put the thing back together
carefully making sure not to make new holes in the rubber.  Next, I cleaned
the back of the fridge especially the air vents.  Finally I took an air
hose and blew high pressure air through both the o2 inlet and the exhaust.
Oh, don't forget to clean out under the fridge when you take it out.  Who
knows, you might find a couple of dead mice there :).  You'll know what
I mean by the word gross when you do get the fridge out.

What I found was that my gas does not cut off all the way from the tank
also.  Did I fix it?  Nope, I figgured it worked well enough till then,
why mess with it.  You'll probably smell some propane when you disconnect
the gas pipes.  I sure did.

When you have your combustion chamber apart, click your piezoelectric
starter to see if you get a spark. If you don't, I can't help much there.

Ok, the results for me were this:  My fridge now runs all night and I even
can see a bit of water vapor (steam) coming out the exhaust ... at least
this after noon I did.

It seems that the manual says that you can tell if the thing needs cleaning
by looking at the flame.  If it is blue, things are ok.  Mine was blue
and things were not ok.  But it seems ok now.

You will also find a bit of info in the bently manual.  I got mine through
interlibrary loan.  Also there is a manual on these fridges which is about
10 pages or so.

Hope this helps.

Stuart Hutton