HELP with furnace in Wheatridge!!!

[bellavite1]

Sounds like you maybe lost a ground to the common side of the transformer. The behavior you describe sounds like a dirty flames sensor but since you've cleaned it, it probably isn't that. I've seen a faulty wiring harness cause the same issue. I've also seen a customer change out a transformer and not ground the common which caused the issue.

Run a wire from the C terminal on the board to a screw holding the board assembly to the furnace.

Ace hardware will most likely NOT have a flame sensor.

You lost me at the C terminal...Which one is it?
Are we talking about where the thermostat wires go in?
That's the only place where I see a C marked on the board.
Or by C terminal we are talking about the neutral strip on the left of the board (thermostat wires being up).