So I've got an older natural gas furnace in my woodshop. Carrier is the brand and I'm not sure of the year built, but its not a high efficiency model (15 to 20 years old??). Anyway the furnace goes out about once a week or so, the pilot light is out when I inspect it. Relight the pilot light and it works great for a few days or more. Anyone out there to offer me some advice on what to look for as the problem?