I am a professional electrical controls engineer in Southern California. I'm designing a low-cost digital temperature monitoring system for Kim Maya, a local chocolatier, who uses the 80 lb machine. The system could easily be adopted to the larger machines. The system will sit on top (electrically) of the Hilliard's controls, so it does not change how the machine normally works, except if the existing control system fails to shut off the heat lamps when the melting temperature is reached (which is what happened to Kim). If the temperature reaches a high, adjustable, set-point (say 120F), the digital system simply shuts off power to the machine. The other neat thing the digital system does is allow the temperature of the chocolate and the temperature and humidity of the shop to be monitored on any device connected to the internet (i.e., cell phone, desk to computer, or laptop) through a free app. The app also can also be used to turn the machine on and off from anywhere (in the world) that has cell phone or WiFi service.
Let me know if you might be interested in having a system installed in your shop. If you're located in an interesting location for me to travel to, I'm sure we can work something out. I have a (mostly) full time job, so this is more of a hobby endeavor, but I do love chocolate.