I bought a used GQF 1202 cabinet incubator several weeks ago. It looks like it is in very good condition. The man I bought it from replaced both wafer thermostats (the regular and the safety set on 102) before I bought it because he says he does it every few years on all of his incubators. He said he ran it for a few days before I picked it up and it held perfect temperature. When I brought it home, I set it up and let it run a day to make sure everything was good, then loaded it up with one tray, plus part of another, full of eggs. Everything went great until day 18 (yesterday). Temp and humidity were perfect with very little adjustment on my part the first 18 days. I candled the eggs with an ovascope yesterday and was delighted that only 10 or so out of the whole batch were no good. When I candled, I would take 6 eggs out of the tray at a time, close the door, candle them, then open the door and quickly put them in the hatching tray and take 6 more eggs out. The door was never open for very long. An hour or two after I did this, I had to leave the house for several hours. When I returned and checked on the bator, the temperature on the thermometer sticking out of the unit was off the chart. I opened the door and black smoke puffed out, and it was extremely hot inside. I'm talking oven-hot. I unplugged it. The inside thermometer glass (one of those cardboard peices with a glass tube with red liquid inside) was broken from the heat and the eggs were literally cooked. Not only were we emotionally devastated from the loss of the chicks, we were terrified that this could have been a much worse situation if we had not checked on it when we did. I called the man I bought it from tonight and he says he's never had that happen in 20 years of hatching out eggs. He thinks that a microswitch must need to be replaced since both thermostat wafers were brand new. Frankly I'm afraid to ever run this incubator again. Any ideas, suggestions, etc. are greatly appreciated!