If you think the combustor not operating properly, do this.

-Check your fuel supply for moisture content. Fuel should be seasoned dried wood. Rain and snow are considered moisture and will produce damp smoke and steam. Both harmful to your combustor, especially when refueling and the combustor is burning hot.

-Check the flue and chimney, making sure the stove’s exhaust system is not blocked nor has any obstructions.

-Make sure the stove is getting the proper draft.

-Check all movable stove parts to be sure they are working freely.

-Make sure the combustor has not fallen out of its holding device.

-Check the combustor for plugged cells. Follow cleaning instructions.

-Check if the combustor has been in the stove for more than six burning seasons, it might be time to replace it.
Be sure to follow the manufacturer’s instructions for proper firing. Different manufacturers and stove models require different procedures.
As a rule of thumb, the catalytic combustor needs a minimum of 500 F. temperature focused on it for a period of 20 to 30 minutes to achieve light-off.  This is done with the bypass in the open position. Nothing but heat will be going to the combustor at this stage. The catalyst will receive the heat it needs in this period of time.