The Dometic manual states to soak the
orifice in alcohol and blow with air.  I soaked
mine and took it to my RV dealer who shot compressed
air throught it since I don't have any at home and it
has worked fine since.

Richard

Here's the Dometic text:
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Periodic Maintenance
Once or twice a year, depending on use, it is necessary to clean and adjust
the burner assembly.
The burner ist fitted with a # 24 jet, which is suitable for use on Propane
or Butane gas at a supply pressure of 11 inches water column pressure. The
orifice in the jet is very small and must never be cleaned by means of a pin
or a similar instrument for this will damage the orifice. Should, for some
reason, the jet require cleaning, it should be washed in alcohol and blown
dry with air.