I live in Chicago. The heating unit is giving me problems. I think it's an Armstrong 48MGE12A18A-1C. Help is kindly appreciated.

I have, what I think is, an Armstrong 48MGE12A18A-1C. I have [pictures] (http://imgur.com/a/h5YRx) and a [video] (https://vid.me/Vsdj) to show better the problems I am having.

This unit has been giving me problems in the past. The burners are lit by a spark plug. Last winter, one day, the unit simply stopped lighting. I had no idea what the problem was, so I called a tech. He wiped the spark plug off dust and a little grime, and gave me a spare spark plug. Everything was working fine after that.

This winter, I've had similar problems. The unit will randomly just not light. I've opened it up, and wiped the spark plug the same way the tech had done. It's worked fine so far.

Tonight I got home, and my condo was cold. Sure enough, the unit had not lit. I wiped the spark plug the same as before, but this time, the spark plug fizzed and sputtered for a little bit, and then stopped arcing. You can hear it sputtering in the video. It lights sometimes, but most times it stops arcing before it lights.

I tried the spare spark plug, and the same thing happens. So then I wiped down the heat probe, since it had a little bit of dust on it, and still nothing.

I managed to light it with a barbecue lighter I have, and I can hear the spark plug arcing with the lit flames, same as when it was working normally, and then stop sparking when, I assume, the heat probe tells the controller the unit is lit.

I don't know if there is anything you can do to help me, or if I should just call a tech to come over. Thank you for anything that you can do.