Well I just finished changing the temp probe on my FEC100. Boy it was a pain. It takes 2 people and about 60+. You basically have to remove the entire hopper assembly to gain access to the side of the smoker where the probe is located. Once that is out of the way, the actual replacement was easy.
the problem with my prob was that the wires had the outside insulation worn off and were shorting out on the outside of the smoker. The issue was that the external plate where the wires exit, the hole was too small. So I made the hole larger, and also double wrapped the wires with a layer of electrical tape. Put it all back together and it works :-)