You could also look for the thermostat/coil. However, it may be difficult to find too. See group 3.640 at http://www.thefirstgensite.com/library/partscounter/number/fec/fec5.html

I found one for mine on EBay a few years ago and still need to install it. Those parts often failed and the valve rattled like crazy in the manifold. I found it better to have the valve wired open than to listen to the rattle. Don't think I've had the valve working for 45+ years.