On my 20 year old 4 burner gas stove, 2 burners work fine. The 3rd has a cracked electrode ("clicks" once, but must light with match) and the 4th is intermittent (sometimes fine, other times 1 "click", then must light with match). I have watched some "how to" videos, but can't seem to grasp if it is just electrodes I need for both burners, or if I need more than that, like a switch or module. Any of you gurus have any advise for me? Thanks!