Also I'll add that as others have suggested you should definitely check that the air intakes are operating properly and non-obstructed. I looked at the exploded view and I dont see a regulated secondary intake like the cat models have.
In the image below I have circled where the primary intake is on the back of the bottom casting. With the stove cold look back there and work the primary air handle - you should see the door open up. It will probably open completely at less than half travel on the handle - this is due to the bimetallic thermostat action. Also check there is no ash or creosote blockage.
In the image below I have circled where the primary intake is on the back of the bottom casting. With the stove cold look back there and work the primary air handle - you should see the door open up. It will probably open completely at less than half travel on the handle - this is due to the bimetallic thermostat action. Also check there is no ash or creosote blockage.