Thanks for the replies. This machine will only see very light usage, so I'll keep using it occasionally for now.
I'll keep in mind that it will need a complete overhaul with a new transmission etc. For historical/nostalgic reasons, I'd like to keep this machine running in its original configuration with a pitman transmission and Power-Fin agitator. Finding parts will be a challenge.
John, thank you very much for checking your stock of modulating gas burners. If I'm ever able to acquire one, that will be a fun project!
Mark