Most of these refrigerators don't get much attention until there is a problem, so I would start by giving the unit and it's cabinet a good cleaning. Make sure there are no mud dauber nests on the coils. Also, spiders really like the smell of propane
odorant so they will make their nests in the burner. A fine, soft brush will get the cobwebs out, as will compressed air. Be careful with the air, as it will blow the jet right out.
Here is a link that will show you how to clean the burner.