spiders love to build nests in the passages.
could be a clogged burner, i remove burner and wash it out with a garden hose
while the burner is removed turn on the gas valves and check for flow....
no flow means its a clog somewhere, a tank with a problem, or what no one has mentioned a bad regulator......
my gas grill must be 40 years old, its used a lot even in mid winter. I have rebuilt it many times.
its a working keepsake, my moms and one of the few things i have of hers.
Its a high BTU lava rock grill, i doubt new ones are made today.....
over the years near every part has gone bad, worn out or failed in some way. i am a super tech on this grill.....:)