My Gas heater won't turn on. The mercury thermostat on the wall is a ITT T99BV303J. It's a small square box that opens to reveal the mercury tube that has 2 wires coming out the end that appear to be attached to nothing. On both sides of the tube are 2 screws that have a white wire attached to each. The wire attached to the left screw is short and leads to nothing. The one on the right goes into the wall behind the thermostat. At the bottom of the mercury tube is a copper coil and under that is a white wire that should be attached to something and is not. My guess is that it should be attached to left wire. Anyone have a diagram of what is should look like when I open the thermostat box?

Thanks for any help.

Don Picoli