When the fire won't draw properly

I noticed that my Backyard Bistro wood fired oven was not drawing properly and creating alot of smoke.  Finally, I noticed that the screen arrester on the exhaust pipe just below the china hat was clogged shut.  A quick cleaning, and it's back to normal.  Tonight I cooked pizza for a friend who lost his wife recently and some awesome ribs for our supper using the hotter version of Fletcher's barbeque sauce.  These were ribs left over from our wood roasted prime rib dinners.  They were awesome!