I have a one year old 10 cpm I bought from AM/fM energy. It is a refurbished model. I keep the stove very clean with tips from this forum. This week after burning for a few hours the stove shut off and i had a burn grate full of unburnt pellets. Has happened five times now. I am burning green supremes from HD. Burning on setting 5, bottom numbers are 3 5 1. Used Stove Chow last year with no problems...4 ton... please help