I've done some pretty good cleaning on my St. Croix hastings, but the glass still seems to be getting dirty faster than it used to. The only thing left that I can assume is that there's not enough air getting in there? I can't tell where the air feeds in on this stove. The manual doesn't really tell me. The flame looks slightly lazier than it used to and I can only assume it's an air flow issue. There's a thin tube coming out of the fan on the left side of the stove that goes from the fan to the front side of the stove. I'm assuming that blows air in, but how would I clean that or verify that I have proper air flow? See the pictures below attached.