i dont think there is any build up, it was restored and during the restoration it was power cleaned, so nothing is dirty... however there might be some of the cotton left over (backstory: manufacturer left cotton or someone built a nest in the radiator i bought and there was a ton of it in the system but i flushed it for 4 hours) but i doubt that would cause any issues, and water flows very well too. anyway ill do what Jon G suggested, and just purchase an original assembly and rebuild it (if needed). my grandfather gets his meds by mail and they use dry ice half the time, and if not, my father could easily get some from the countys medical supply, as for ether, im not sure where id get it, im sure its in the medical supply though.
