The furnace smelled funny last time I took the trailer camping. The furnace is 60 years old so I removed it and checked for leaks. None were found, but a gasket was worn so I used some sealer, then put it all back together. Below are pictures of the Carlson 6m furnace to help those that want to do the same. Note the  “revolutionary” horizontal vent used for the first time on the bambi that saved a lot of space because airstream no longer needed a chimney to the top of the trailer.