I have a problem I can't solve on my own. I have tried to hire several persons but it isn't a lucrative enough job and no one is interested. Problem, I have an older incubator with the wafer and snap switch type controls and the snap switch went bad. I wanted to upgrade from this type of controls anyway so I bought controls from the Petersime Incubator Company. I hope this description is understandable to someone. These consist of a box with a face plate made of some sort of composite material. The plate has 2 clips, similar to the old automobile type fuse block clips. There is a glass "thermometer" a tube that contains mercury and has 2 metal bands around it and a wire that go through the tube and these bands, the bands snap into the clips. When the temp rises to the proper level the mercury expands and contacts the wire and shuts off the heating element. There are also 3 terminals on the front side of this face plate, Red, White, and Black that extend through to the back side. There is a brass bar from the white terminal to one of the clips. It came with a moveable jumper wire attached between the black and white terminals. I have no idea if this is relevant or not. Screwed onto the back side if the faceplate is a block that says "Douglas Randall solid state relay, model a25a nc". There are 4 screw down terminals (at least that's what I think they are called) numbered 1,2,3,4, there is a line drawn between 1 & 2 with what appears to be a switch symbol in it, on the left side of the "switch" it says 120 vac on the right side of the "switch" it says 25 amperes. There is a line between 3 & 4 with a circle in the center, on the left side it says 90-260, on the right side it says vac. There is a red wire from the bottom of the plate (the red terminal) to # 1 on the relay. There is a black wire from the black terminal to #2 on the relay. There is a yellow wire from the clip where the metal band on the thermometer snaps in to #3 on the relay. There is a brass bar between relay terminals 1 & 4. On the old controls there were 2 wires 1 white and 1 black. The new seems to need 3 wires. How do I proceed from here? Any help will be appreciated.