Ran through the first 20 bags of Green Supreme and everything was great. Few days ago the glass started to get black and pellets started mounding in the middle of the pot and clinkers around the inside of the burn pot started shutting down the air flow after 1/2 bag. Cleaned the stove, changed settings from 2-5-1 to 1-4-1. Same thing. Cleaned again, changed settings to 1-6-1. Same thing. When the fire starts out it roars like a blast furnace for a few hours then, black glass and clinkers and lazy flame. I've tried running top buttons at 2-3, 5-5, 7-9. No change. This just started a week or so ago. Any thoughts? Thanks.