Pulses manufactured after a break date are supposed to be immune from the problem. It was only starting to show it's head when I left and went to work for Motorola. They are/ were one of the most efficient furnaces made. How often do you have it serviced? The big maintenance item is the air flapper material, and on later ones, the non metallic horn on which they mount. The gas flapper is in the elbow assy down below the silencer, below the gas valve. They can fail, but not often
Other big maintenance is simply keeping them clean. Remove/ clean/ lube the blower and motor, and clean the secondary heat exchanger fins. I used to use a big low storage bin for "catch" and a week sprayer with "coil clean."
Once in awhile the flame sensors fail. They resemble a spark plug with 10mm threads. The ignitor IS a spark plug don't remember the number. Access by the small door at bottom left