I have a 1968
Tradewind with a non-functional original heater. I researched the "heater" forums discussions here and learned that new replacement parts are not available and used parts are suspect at best. You end up putting lots of dollars in used parts into a 40+ propane heater that you hope will work. If the heater were in your home, you would have replaced it 20 years ago.
Being from Georgia, I do not camp after November nor before March. To burrrr cold for me.
I found that can heat the whole 24' trailer with a small electric 110v "milk house" heater with an electric fan blower and thermostat, that I purchased for $30.00.
And if I removed the old junk heater for under the kitchen sink I gain a lot of storage space.