Dual Burner gets hot, but not to normal Hi temperature

Brand: Kenmore
Model Number: 790.96112406
Main Symptom: Dual burner is low power instead of Hi
What happens & when: always, now

Error Code (if any): none - burner clearly not as bright (hot) as others on Hi setting
Parts or tests already tried: none
Photos / video link:

My dual burner on the right front no longer heats to Hi, with either the small or dual burner, but it does get hot. The surface no longer glows as bright as the other burners when they are on the Hi setting. This started while boiling water for spaghetti, and the boiling disappeared when the burner went to the lower power.

Since this isn’t a total failure, the exact problem isn’t obvious. Does anyone have a good way to determine what has failed? I don’t really want to replace all the dual burner parts, if only one is bad. I have a digital multimeter and other test equipment and tools, if measurements are required.

Thank you!

Test to ensure you have a full 240vac to the burner. If you do, the burner is the issue; if not, it is the control.

Thanks - looks like it’s the burner.