The combo burner on my KA cooktop only works as a big burner no matter what position the knob is in. If it's on the small burner settings, both the small and large elements heat up. On the large settings, both also heat up. So basically I can't use it as a small burner. Is the knob assembly to blame, and if so is it an easy swap?

Thanks. How could it be the burner as both of the elements of the burner do work (though not at the right time)? Seems as though it's either a stuck switch contact as noted in the video link or perhaps incorrect wiring (seems unlikely).

I can't easily diagnose as it's at a vacation home that's a couple hours away, thus I'd like to narrow it down as much as possible and order parts before I go there next.