Thanks for all the helpful responses on lighting
the fridge in my '87 Westfalia.  It sounds like
different things work for different individual fridges.
Here's what worked with mine; fortunately, I didn't
have to remove the fridge:

  - Vaccuumed out the condensation drain (had a terrible
    time unscrewing the plug), all vents, and both flues
    (after removing ouside fittings).
  - Ran the fridge for a few hours on 110, and then for
    a while on 12V.  Some people said they have to run
    it on one or the other for a while before they can light
    it on LP.  I don't now - it now works without this step.
    Maybe this helped mine get going somehow - I don't
    really know.
  - To light, I turn on the gas valve, set the thermostat to
    max, pump the air pump 30 times, and immediately
    push in the gas button while simultaneously sparking
    repeatedly until the "lit" LED on the monitor panel
    slowly starts to glow.  Takes about 10-20 sparks.
    All this must be done quickly.
  - The sight hole in the fridge is pretty much useless,
    unless you happen to be at exactly the right angle and
    in the dark, in which case you can see a hint of blue
    flame.  I'm guessing it's out of alignment.

The fridge now works pretty consistantly.

A minor question: my flue cap is missing.  I figure I'll use
a big butter tub or something, rather than buying a new one.
But I was wondering - what holds the original flue cap on?
Just pressure against the rubber seal?  Does it stay on
securely? Thanks.