I did a quick clean of my stove this weekend; I get lazy at the end of the year. Anyway,in the 2 days since the cleaning, the glass was already half black, brick was blackened and it had a floppy flame, etc. Decided to do a thorough cleaning. Once done with the stove itself, went out to the vent and the screen was plugged with ash. Duh, should have checked that first. I think what happened is I tried another pellet last week, my Turman's got jealous and got back at me by plugging up the screen. I can't think of any other reason because this rarely happens.