I have had a few fail in my hands, there is a faint smell of alcohol and then it won't read any more. While I have not studied on it, it appears that there is fluid in the lead that communicates some combination of temperature and/or pressure to the read-out dial.
Now, with that said, if they could put that stuff in there to begin with, there should be a way to replace it, sort of like Freon in an air conditioning unit.