Also check rated heat input on the plate and ensure that the orifice and pressure combination provides that input. Secondary air path. Burner and pilot. These should be cleaned. The good news is that most ovens can easily be repaired so that they emit little or no CO in the exhaust port, typically below 100 ppm peak or 25 ppm steady state.
Ovens are basically simple devices, and repair tools cost little.
A small brass wire brush, flair wrenches, and an asbestos glove are used for tuning as well. Kitchen Exhaust Fans Ventilating combustion products directly out of the kitchen eliminates the opportunity for them to affect occupants. This would get rid of CO and also oxides of nitrogen that are always present. These pollutants are a special concern in tight houses. Kitchen fans are generally noisy, in part because they have relatively high flow rates.