Inspect This, Picture #2
The gas line being used to serve this furnace is dated. The American Gas Association no longer considers this type of line to be acceptable for use in many areas of the country and recommends that either a Tephlon coated or stainless steel line be used. The gas line servicing the equipment also enters the casing of the furnace without the benefit of bushing protection.
Comments are welcome edmartin1@juno.com