Product review (5 stars): Fixed that pesky burner
We'd been having to hand light that pesky burner for over a decade.  I'd always been told  it was the sparker module (about $100 to replace).  Recently it was getting worse about re-sparking when the burner was already lit.  So I did some reading and found the both the lack of lighting and the resparking can be caused by this little electrode.  Apparently, it not only lights the burner, but also acts as the flame sensor.  A comment said if it's cracked, it can cause the re-sparking.  Sure enough, my old one was cracked.  Removing the cooktop from the counter isn't all that hard.  Turn off gas, disconnect gas hose (should be compression fittings to unscrew) unscrew any anchor straps (I didn't reinstall mine.  Cooktop's not going anywhere),  unplug.  Lift top out of counter hole and flip over onto a soft towel or something.  Remove 10 or so screws holding back panel and remove that.  Petty simple inside.  Pry spring clip from offending sparker and it'll come right out.