So I have a Weber Genesis (silver B I believe) and love it, used it
very successfuly for a year now. However, I just noticed the past
couple times I've used it that it is taking much, much longer to heat
up than it used to. For most of the first year, my biggest problem was
keeping food from burning as the heat got so high so fast. Now, it
takes forever to grill anything. It didn't seem like a gradual problem
either, more like a sudden onset of weak-heat sickness.

I checked the gas and the tank seems pretty full, there's just not a
lot of heat coming out anymore. Any ideas of what could cause this?
Is there something I need to clean off or clear out?

Thanks in advance.