I just had National Grid (gas Company) and he used some sort of meter on it...it stayed zero for almost the whole time he checked with it going to 0.05 briefly. He said that there may be something wrong with the gas valve but since he was not a plumber or HVAC guy he could not be sure.
In any event he said that everything checked out fine even with that minuscule reading...he used that meter on every connection he saw in the furnace and in the cellar and it all checked out at either 0 or 0.05
He said if he thought there was any danger he would have shut everything down and red flagged the place
If it is the gas valve is that a difficult and costly repair?
The smell seems to be coming from this opening but this opening has always been here..it looks like it is supposed to be there
Could it be the gas valve is allowing gas to get into burn chamber when it is not supposed to be?
Like I said the gas company guy said the meter is very powerful and if there was a danger it would have picked it up
Thoughts on next step...if I walk by the furnace you don't smell it..if you stick your face inside you get that faint whiff