Jerry, I've not had your problem, but I think you are right about the way to access it. In my experience with gas appliances, spider webs can seriously interfere with lighting of heaters if they are formed inside the lighting areas. Also, there is a thermocouple there that senses heat to determine that the furnace has actually lit and if it's dirty, it won't register the flame properly. You simply wipe it off (a service technician wiped the one in my house furnace off on his jeans one time, and it worked like a charm).
I think there's also something called a "sail switch") that can maybe get "stuck". I seem to recall this from many years ago in a post on this forum.
Perhaps someone with better knowledge than I on this appliance will notice this thread and chime in.
- Jack