I have an older Intertherm natural gas furnace model number MG H(stamped) 075A A(stamped) C

The pilot light will ignite and remain burning.
The fan operates in the ON(when required)and Fan(constant)positions.
There is 24 volts leading from the transformer to my digital 24 volt thermostat.
The thermostat is working.

However, I can't detect any voltage at all on the two terminals of my Unitrol gas valve controler.
A black wire comes from the heat limiter and a brown wire is attached to the ground connector on the furnace.
If there is no power at the black wire then the secondary electromagnet for the main gas valve should not work.
This seems to coincide with the burners not igniting upon command from my thermostat.

Does anyone know why there is no power to the Unitrol unit?
Could it be a faulty transformer or relay in the transformer?
What are my options?


The gas contractors all say that the furnace needs to be replaced (of course) for a mere $2,700.
Thank you in advance for any suggestions.

Sincerely,
Douglas.