I have an Advantage II pellet stove bought in 1995. I cannot get air to the burn chamber underneath the grate. I have completely cleaned the stove but when I turn on the air it does not reach the area underneath the burn grate so as a result I get a lazy flame that goes out after a short bit. The air is felt coming out of the left side of the stove right near the start of the door for the burn chamber (stove door). What do you think is going on and how can I correct this. Just started to happen this year. Thanks Kem