I have a Trane XL80 furnace that buzzes. It works fine, just has a constant hum that recently has gotten louder. I can't find the posts I read before, but one mentioned there was a converter (or transformer) and the plates on it have loosened up, hence the humming. Also said this part wasn't serviceable and needed full replacement. Whatever it’s called it is directly behind the control board on the other side of the sheet metal wall. I can see the wires go down and up behind the sheet metal. But I have no idea what that part is called. And looking at part lists, nothing obvious pops out to me. Any help is much obliged.