First, check to make sure your ignitors are clean. Food residue can insulate them and prevent efficient spark. Next, make sure the diffusers are clean. Again, food residue and grease can cause an uneven flame, as well as unburnt gas. After cleaning, if you have no spark, or weak spark, you may need to replace the ignitors or the spark module. Please post your results. We can help you with further diagnosis, if necessary.