When I am using only 1 burner (front right) things are OK. When I turn on a second burner (rear right, all 4 ignitors start firing at the same time at +/- 1 second intervals. Both of the left burners are the adjustable low cooking type (3 sec. on 10 sec. off etc). I've cleaned as recommended in the manual and this seems to work sometimes and for a while but the problem keeps comming back. Do I need to replace the ignitors or is there some control mechanism? Is this something I can do myself? Also, is there a way to convert the low cooking burners (or idealy just 1 of them) to a regular function burner as I seldom have a need for this feature.