Posting to a dead thread, but went through the same thing last Friday.
The incubator is designed to have 2 wafer thermostats. It primary wafer in front of the secondary (backup). It appeared to me that the digital thermostat replaced the primary wafer.
Mine came with the backup wafer removed for shipping. The electronic thermostat was set hot. I installed the backup wafer, and set it to 102 degrees (with the electronic set hot, only the wafer was turning off the heating element (clockwise moves the screw in, causing the wafer to contact the switch at a lower temp).
After the wafer was set at 102, I backed the primary down to 99.5. The electronic thermostat was shipped with the stem removed, so I had to snap that in place-there was a hole in the side of the cabinet to insert it).