Cast Iron Collector Forums - Cast Iron Burners/hot Plates/camp Stove Cleaning

I have a couple propane cast iron two burner camp stoves. Not sure what everyone calls them burners/hot plates/camp stove? Anyways. They are similar to a Griswold 202. They only get used a couple times a year for a few hours. Lately they have both been burning with a yellow flame and make a lot of soot. Adjusting the air doesn't fix it completely. What would be a good way to clean the inside of the burners? Could I burn out anything inside or on the outside by putting them in the coals of a fire? Would that damage them?

There is at least one small screw that is seized in the cast iron. Any recommendations on how to remove it?

I've done a few Google searches on this and haven't come up with much, likely because I don't know what everyone calls them. So if anyone knows of sites or posts about this, post a link or what to search for. I would be interested in how people are refurbishing/restoring these.

Thanks